Apparatus for rolling test of spur gear

Abstract

The invention relates to a method comprising the following method steps: performing a rolling test on a spur gear (16) by means of a rolling test bench (28, 46), statically checking the repeatability and reproducibility of the results of the rolling test and determining a standard deviation for the results of the rolling test; hard finishing the plurality of spur gears; performing a rolling test on the plurality of hard-finished spur gears by means of a rolling test bench whose standard deviation has been determined; off-line testing of the plurality of hard finished spur gears by means of a transmission test bench (58); analyzing and processing the offline test results of the plurality of spur gears subjected to hard finish machining, and declaring the spur gears as qualified parts or defective parts; and analysing the results of the rolling test of the plurality of hard-finished spur gears, analysing the results of spur gears declared as qualified parts according to the offline test, the results of the rolling test correspondingly comprising order analyses, a tolerance limit being determined for each order or order.

Description

TECHNICAL FIELD

[0001] The invention relates to a method for a rolling test of a toothing and in particular to an apparatus for a rolling test of a batch production of spur toothings or spur gears. BACKGROUND

[0002] The increasing importance of the noise behavior of vehicle transmissions leads to the fact that spur gears are also increasingly subjected to a rolling test or an off-line test, which examines the dynamic behavior of the spur gears involved and in particular the noise behavior. A corresponding manufacturing process and quality regulation loop is known, for example, from the document WO2022207371A1.

[0003] The problem arises in the manufacture of spur gears that the tolerances for the rolling test are not known in advance. An apparatus for a rolling test of a batch production of spur gears is therefore complex or can only be carried out in many cases by experienced or specially trained staff. SUMMARY

[0004] Against this background, the technical problem on which the invention is based is to propose a method which enables a robust and reliable rolling test of spur gears and in particular generally reduces the test costs.

[0005] The technical problem described above is solved by the features of the independent claim. Further design options of the invention result from the dependent claims and the following description.

[0006] The invention relates to a method comprising the following method steps: rolling test of spur gears by means of a rolling test stand, wherein the repeatability and reproducibility of the results of the rolling test are checked statically and the standard deviation for the results of the rolling test is determined; hard-finishing of a plurality of spur gears, wherein the respective toothing of the respective spur gear is hard-finished; rolling test of the plurality of spur gears which have been hard-finished by means of the rolling test stand for which the standard deviation has been determined; off-line test of the plurality of spur gears which have been hard-finished by means of a transmission test stand; analysis of the results of the off-line test of the plurality of spur gears which have been hard-finished, wherein the spur gears are declared as good pieces or as defective pieces in accordance with at least one quality criterion; analysis of the results of the rolling test of the plurality of spur gears which have been hard-finished, wherein the results of the spur gears which have been declared as good pieces in accordance with the off-line test are analyzed, wherein the results of the rolling test accordingly comprise an order analysis, and wherein for one or more orders one tolerance limit each is determined.

[0007] According to the application, therefore, the results of the end-of-line test form a reference in order to define the good pieces and the bad pieces, wherein one or more order-specific tolerance limits for the rolling test are determined in such a way that the results of the rolling test of a spur gear which has been declared a good piece of the end-of-line test are taken into account.

[0008] In this way, one or more order-specific tolerance limits for the rolling test can be determined by means of the end-of-line test, wherein the results of the end-of-line test are compared with the results of the rolling test.

[0009] The tolerance for the rolling test can therefore be determined and set by means of the process flow given according to the application.

[0010] In this way, a reliable and robust rolling test of spur gears can be achieved.

[0011] Preferably, the rolling test can be a single-sided rolling test. Alternatively, the rolling test can be a double-sided rolling test.

[0012] The rolling test stand for the rolling test and the transmission test stand for the end-of-line test are two separate, mutually different devices. In the context of the rolling test, the spur gear to be tested is rolled with a standard gear (Meisterrad) in a known manner in order to determine, for example, the rotational error or similar deviations. The end-of-line test involves an acoustic test of the respective spur gear to be tested in the assembled state in the transmission housing. That is to say, the toothed portion to be tested is tested on the end-of-line test stand in accordance with the real installation situation with the respective surrounding bearings and adjacent spur gears or in a gear set pairing (Radsatzpaarung) set up for application. In particular, a complete assembled set-up for delivery of the transmission can be tested on the test stand by means of the end-of-line test.

[0013] The respective spur gear can be a spur gear with external toothing.

[0014] The respective spur gear can have a straight toothed portion. Alternatively, the respective spur gear can have a helical toothed portion.

[0015] The respective toothed portion of the respective spur gear can have modifications, such as Balligkeiten, Rücknahmen or similar structures.

[0016] In the method according to the application, first the repeatability and reproducibility of the rolling test is checked. The check can also be referred to as a "Gage R&R" test, a term of art for a check of the capability of the measuring system involved for a defined measuring task. Here, inter alia, it is tested whether the combination of the rolling test bench and the standard gear used and the clamping of the tooth part to be tested provides reproducible, repeatable results. In this way, for example, defects or wear of the rolling test bench or of components of the rolling test bench, the standard gear or the clamping can lead to a substantial divergence of the results of the rolling test or to random results. In the case in question, the test setup has to be corrected until the repeatability and reproducibility are ensured.

[0017] The spur gear for checking the repeatability and reproducibility is rolled during the rolling test with the same or identical standard gear which is also used in the further process, inter alia, for the rolling test of the mass production. Thus, the spur gear for checking the repeatability and reproducibility is based on the same nominal geometry as the further spur gears.

[0018] The hard finishing of the spur gear can be implemented, for example, by means of a grinding method. Here, a continuously indexed grinding method can be involved, such as, for example, indexed roll grinding by means of a grinding worm, or a single-tooth indexed grinding method, such as, for example, form grinding or indexed roll grinding by means of a grinding wheel.

[0019] The respective spur gear is hardened before the hard finishing.

[0020] The check carried out on the respective spur gear in the off-line test is a check of the acoustic properties. Quality criteria of such an off-line noise test are, for example, the sound pressure level, the air-borne sound, the structure-borne sound, the loudness level, the loudness of the transmission noise, but also, for example, the tonality, i.e. the extent to which the dominant frequency of the transmission noise is audible as a disturbing single tone. A known analysis of the noise properties by means of an off-line test is the so-called noise vibration harshness (NVH) criterion, in which the abbreviation NVH stands for "noise" (German: Geräusch), "vibration" (German: Vibration) and "harshness" (German: Rauigkeit). In this way, it can be provided that the off-line test has a limit value for one or each of the above-mentioned features for the noise evaluation, which the respective spur gear has to comply with in order to be declared as a qualified piece.

[0021] The order analysis represents the results of the rolling test as an order spectrum. Here, individual orders and / or order ranges of the order spectrum can be assigned test features of the tooth system, such as the concentricity error; the runout; the indexing error of the first and / or higher orders; the surface waviness, the error of the tooth surface shape or similar features.

[0022] The results of the rolling test are created, inter alia, by providing the rotary-related axis data of the rolling test stand as an order spectrum by means of a fast Fourier transformation (FFT). The abbreviation FFT here represents the fast Fourier transformation in the known manner (English: fast fourier transformation). The orders here are multiples of the revolutions of the spur gear on the rolling test stand, such that the measured deviations or measured values are plotted as amplitudes with respect to the individual orders.

[0023] The application of the off-line test and the NVH criteria and the assessment of further acoustic features in the context of the off-line test are prior art and sufficiently known. The same applies to the rolling test and the order analysis associated therewith. The present application here is the application of the off-line test in order to determine the tolerances for the rolling test from the off-line test qualified pieces and thus to simplify the equipment of the rolling test.

[0024] It can thus be provided that the spur gears that have been declared as qualified pieces in the off-line test are used as a reference for determining the tolerances for a plurality of orders, which are used in the context of the rolling test for series production.

[0025] It can thus be analyzed, for example, which three spur gears that have been declared as qualified pieces in the off-line test have the greatest amplitudes for the first order of the rolling test in the rolling test. The average of these amplitudes can be determined as a tolerance limit for the first order, the compliance with which is checked during the rolling test of further spur gears in series production. Alternatively, the maximum value of the amplitudes for the orders involved can be determined and determined as a tolerance limit for the orders, wherein only the qualified pieces of the off-line test that serve as a reference are analyzed again.

[0026] During the setup of the rolling test, the hard finishing, the rolling test and the off-line test can be carried out at least partially simultaneously for different spur gears. The sequence of the rolling test and the off-line test is arbitrary during the setup of the rolling test, wherein, preferably, the rolling test of the spur gears involved is carried out in time before the off-line test.

[0027] The steps explained previously describe the setup of the roll-off test and the comparison of the roll-off test with the end-of-line test, whereas the actual mass production is subsequently referred to as hard finishing of "further spur gears". Thus, the roll-off test set up in this way is applied to the further spur gears or the respective production batch in order to test the quality of the further spur gears involved with respect to the determined tolerances within the scope of the roll-off test.

[0028] Thus, the hard finishing of the further spur gears and the roll-off test of the further spur gears can be carried out after the setup of the roll-off test, wherein the results of the roll-off test of the respective further spur gears accordingly comprise an order analysis, wherein the compliance with the respective determined tolerance limit is checked for one or more orders of the respective order analysis.

[0029] It can be provided that the end-of-line test is carried out for those of the further spur gears for which the determined tolerance limit is not complied with. That is to say, spur gears which do not comply with the predetermined tolerance limit during the roll-off test, that is to say, which are declared to be rejects according to the roll-off test, can be delivered for comparison in the end-of-line test.

[0030] The end-of-line test either results in the fact that the results of the roll-off test are correct and the spur gears involved are actually rejects, or it results in the fact that the roll-off test can be incorrect, the spur gears involved should be declared to be good pieces according to the end-of-line test and the tolerance limits of the roll-off test can be adapted accordingly if necessary. In this way, a quality regulation loop for the roll-off test can be created, the method of which is to compare the roll-off test periodically with the end-of-line test in order to achieve the best possible correlation between the end-of-line test and the roll-off test.

[0031] It can be provided that, if the end-of-line test of the further spur gears results in the fact that the further spur gears should be declared to be good pieces according to the quality criteria of the end-of-line test, the tolerance limit of the order is adapted for which the order analysis according to the roll-off test does not comply with the tolerance limit for the further spur gears.

[0032] By means of the approach according to the application, the scope of the end-of-line test can be reduced, in particular. Insofar as a good correlation between the roll-off test and the end-of-line test is achieved, it is thus not necessary to deliver every spur gear to the end-of-line test, since the results of the roll-off test already form a sufficiently good prediction of the results of the end-of-line test. Thus, it can be provided, in particular, that the respective spur gears of the further spur gears which comply with the determined tolerance limit are not subjected to the end-of-line test.

[0033] Alternatively or additionally, it can be provided that individual spur gears are delivered to the end-of-line test in a sample manner, randomly or at determined time intervals or after the manufacture of a determined number of components, independently of the results of the roll-off test, in order to check the correlation of the roll-off test and the end-of-line test.

[0034] It can be provided that 100% of the further spur gears are subjected to the roll test. This means that all further spur gears are delivered to the roll test. However, based on the correlation between the roll test and the end-of-line test, it is not necessary that all spur gears are also delivered to the end-of-line test. Rather, according to the present application, only a number of the further spur gears of the further spur gears is delivered to the end-of-line test. The number of further spur gears delivered to the roll test is thus greater than the number of further spur gears delivered to the end-of-line test. In this way, the test time can be greatly reduced.

[0035] As already discussed above, the one or more tolerance limits can also be subjected to further monitoring and adaptation after the roll test is set up by means of the end-of-line test in order to improve or permanently ensure the correlation of the roll test and the end-of-line test.

[0036] The present application also relates to a device for the roll test of spur gears or spur gear sections in series production, the device being used to carry out the method according to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0037] The present application is described in more detail below on the basis of the drawings, which show embodiments. The drawings show schematically:

[0038] Figure 1 The method steps of the method according to the present application are shown;

[0039] Figure 2 A gear machining machine is shown;

[0040] Figure 3 An index roll grinding of a spur gear is shown;

[0041] Figure 4 A device for single-sided roll testing is shown;

[0042] Figure 5 A device for double-sided roll testing is shown;

[0043] Figure 6 An end-of-line test is shown. DETAILED DESCRIPTION

[0044] In the method step (A), the spur gears are first subjected to the roll test by means of a roll test bench, wherein the repeatability and reproducibility of the results of the roll test are checked statically and the standard deviation of the results of the roll test is determined.

[0045] The results are shown schematically in Figure 1 in (A), wherein a spectrum of orders for the rotational error is created and each order is assigned a standard deviation in the form of an error column F.

[0046] Subsequently, the plurality of spur gears is hard-finished according to step (B), wherein the respective toothings of the respective spur gears are hard-finished, and the hard-finished plurality of spur gears is roll-tested by means of a roll test stand for which a standard deviation has been determined. Furthermore, the hard-finished plurality of spur gears is end-of-line tested by means of a transmission test stand and the results of the end-of-line testing of the hard-finished plurality of spur gears are evaluated, wherein the spur gears are declared as good pieces or as bad pieces according to a quality criterion. Herein, for example, known NVH evaluation or NVH criteria of the end-of-line testing can be involved.

[0047] Figure 1 The results of the roll testing of the hard-finished plurality of spur gears are shown in (B) as order analysis of the spur gears which have been declared as good pieces within the scope of the end-of-line testing.

[0048] The maximum value of each order from (B) is used together with the standard deviation from (A) for determining a tolerance T for the respective order of the roll testing. The determination of the tolerance is shown in Figure 1 diagram (C). Thus for each considered order it is investigated which of the hard-finished spur gears declared as good pieces according to the end-of-line testing constitutes the largest deviation for the involved order and the deviation is determined as upper tolerance limit for the respective order.

[0049] Thereby, according to step (C) the set-up of the roll testing is first ended and the hard-finishing of further spur gears can be performed and the roll testing of the further spur gears can be performed, wherein the results of the roll testing of the respective further spur gears respectively comprise an order analysis and wherein for one or more orders of the respective order analysis the compliance with the respective tolerance limit determined according to step (C) is checked.

[0050] For further spur gears for which the tolerance limit determined according to step (C) is not complied with, the end-of-line testing can be performed. If the end-of-line testing leads to a contradiction to the roll testing that the spur gear is a good piece, the respective tolerance limit of the roll testing can be adapted according to the spur gear in such a way that the amplitude of the involved order is used as a new corrected tolerance limit TK for the subsequent roll testing. The way is illustrated in Figure 1 .

[0051] As can be seen in step (D) thus, TK is above the initially determined tolerance limit T. Thus, for the involved order the tolerance limit T is raised to the value TK.

[0052] That is, if the off-line test of the further spur gear results in that the further spur gear should be declared as a good piece according to the quality criteria of the off-line test, then the following tolerance limit of the adapted order is not followed by the order analysis of the rolling test for the further spur gear.

[0053] The off-line test thus forms a reference, wherein the tolerance of the order of the rolling test is adapted according to the off-line test in order to achieve the best possible correlation of the rolling test with the off-line test.

[0054] Figure 2 A gear machining machine 2, i.e. a gear grinding machine 2, for hard finishing of spur gears is shown. The gear grinding machine 2 has a tool spindle 4 for holding and rotating a driving grinding tool. The gear grinding machine 2 has a workpiece spindle 6 for holding and rotating a driven toothed spur gear to be ground. The gear grinding machine 2 has a dressing device 8 for dressing the grinding tool.

[0055] The gear grinding machine 2 has digitally controlled machine axes X, Y, Z, A, B, C, C2, B2 for performing translatory and rotational relative movements in order to provide the required machining kinematics when gear cutting or dressing. Furthermore, the gear grinding machine 2 has an axis Z1 with a movable pinole 12 for clamping a shaft or a clamping arbor.

[0056] Figure 3 The tool spindle 4 with a dressable grinding worm 14 held thereon and the workpiece spindle 6 with a toothed spur gear 16 to be ground held thereon are shown exemplarily and schematically, the toothed portion 17 of the spur gear being ground.

[0057] Figure 4 The schematic structure of a test stand 28 for carrying out a single-face rolling test for a respective spur gear 16 is shown exemplarily.

[0058] The test stand 28 has a first drive 30 and a second drive 32. The first drive 30 is designed for driving a first shaft 34, on which the toothed spur gear 16 to be tested is mounted.

[0059] The second drive 32 is used for braking a counter gear 36, which is mounted on a second shaft 38 coupled with the drive 32.

[0060] The counter gear 36 is a spur gear with external teeth, i.e. a standard gear, which meshes with the toothed portion of the spur gear 16. By driving the spur gear 16 and simultaneously braking the counter gear 36, the number of revolutions and the torque can be set during the test. It goes without saying that the revolution and torque profile is also settable. The axis spacing al between the shafts 38, 34 is constant.

[0061] The test bench 28 has a rotary encoder or angle measuring system 40, a rotational acceleration sensor 42 and a solid sound sensor device 44.

[0062] Alternatively or additionally, a double-sided rolling test can be carried out. A test bench 46 for a double-sided rolling test is shown exemplarily and schematically in Figure 5 For the avoidance of repetition, the same reference numerals are given to the same features in the following.

[0063] The double-sided rolling test differs from the previously described single-sided rolling test according to Figure 4 essentially in that the axis spacing a2 is not constant during the test. The counter gear 36 is mounted and supported with its shaft 38 on a movable slide 48. The movable slide 48 is supported on an immovable counter support 52 by means of a spring device 50.

[0064] The counter gear 36 is pressed by means of the spring device 50 in such a way that it comes into tooth contact with the toothed portion of the spur gear 16 to be tested, wherein there is a two-sided contact, not only on the right side but also on the left side, of the toothed portion of the spur gear 16 to be tested in the tooth contact.

[0065] During the test, i.e. during the rolling of the toothed spur gear 16 with the counter gear 36, the counter gear 36 is pressed in the direction of the spur gear 16 with a defined force.

[0066] The deviation is detected from the translational displacement of the movable slide 34, wherein the slide 48 is provided with a displacement sensor 54 and a vibration sensor 56 in order to receive the measurement data. The single-sided rolling test and the double-sided rolling test are state of the art.

[0067] Figure 6 A line-out test bench 58 is shown, wherein the spur gear 16 to be tested is mounted in a transmission housing 60 and is paired with a counter gear 62 provided for delivery. This enables an acoustic investigation, i.e. an analysis of the transmission noise with regard to one or more quality criteria. The line-out test is state of the art.

Claims

1. Method, comprising the following method steps: - rolling testing spur gears (16) by means of a rolling test stand (28, 46), statically checking the repeatability and reproducibility of the results of the rolling testing and determining a standard deviation for the results of the rolling testing; - hard-finishing a plurality of spur gears (16), the respective toothings (17) of the respective spur gears (16) being hard-finished; - rolling testing the hard-finished plurality of spur gears (16) by means of the rolling test stand (28, 46) for which the standard deviation has been determined; - end-of-line testing the hard-finished plurality of spur gears (16) by means of a transmission test stand (58); - evaluating the results of the end-of-line testing of the hard-finished plurality of spur gears (16), the spur gears (16) being declared as good pieces or as defective pieces in accordance with at least one quality criterion; - evaluating the results of the rolling testing of the hard-finished plurality of spur gears (16), the results of spur gears (16) being evaluated which have been declared as good pieces in accordance with the end-of-line testing, the results of the rolling testing accordingly comprising an order analysis, and for one or more orders each one tolerance limit being determined.

2. The method of claim 1, wherein, After evaluating the results of the rolling testing of the hard-finished plurality of spur gears (16), further spur gears (16) are hard-finished and rolling tested, the results of the rolling testing of the respective further spur gears accordingly comprising an order analysis, for one or more orders of the respective order analysis a compliance with the respective determined tolerance limit (T) being checked.

3. The method of claim 2, wherein, For the respective spur gears of the further spur gears (16) for which the determined tolerance limit (T) is not complied with, an end-of-line testing is carried out.

4. The method of claim 3, wherein, If the end-of-line testing of the further spur gears (16) results in that the further spur gears (16) should be declared as good pieces in accordance with the quality criterion, a tolerance limit (T) of the order is adapted, for which the further spur gears (16) do not comply with the tolerance limit (T) in accordance with the order analysis of the rolling testing.

5. The method according to one of the preceding claims, characterized in that For the respective spur gears of the further spur gears (16) for which the determined tolerance limit is complied with, no end-of-line testing is carried out.

6. The method according to one of the preceding claims, characterized in that All further spur gears (16) are delivered to the rolling testing.

7. The method according to one of the preceding claims, characterized in that One or more tolerance limits (T) are monitored and adapted in order to improve the correlation of the rolling testing and the end-of-line testing.

8. The method according to one of the preceding claims, characterized in that The rolling testing is a single-sided rolling testing and / or a double-sided rolling testing.

9. The method according to one of the preceding claims, characterized in that The respective spur gear (16) to be tested for the end-of-line testing is assembled in a transmission housing (60), which represents the installation of the spur gear (16) in the delivery state of the completed transmission in accordance with the operating conditions, or which is the transmission housing of the transmission to be delivered.

10. The method according to one of the preceding claims, characterized in that The maximum deviation of an order is determined as a tolerance limit for the order in the scope of the evaluation of the results of the rolling testing of the plurality.

2. Method according to claim 1, wherein the rolling testing is a single-sided rolling testing and / or a double-sided rolling testing.

3. Method according to claim 1 or 2, wherein the transmission housing (60) represents the installation of the spur gear (16) in the delivery state of the completed transmission in accordance with the operating conditions.

4. Method according to one of the preceding claims, wherein the maximum deviation of an order is determined as a tolerance limit for the order in the scope of the evaluation of the results of the rolling testing of the plurality.

5. Method according to one of the preceding claims, wherein the rolling testing is a single-sided rolling testing and / or a double-sided rolling testing.

6. Method according to one of the preceding claims, wherein the transmission housing (60) represents the installation of the spur gear (16) in the delivery state of the completed transmission in accordance with the operating conditions.

7. Method according to one of the preceding claims, wherein the maximum deviation of an order is determined as a tolerance limit for the order in the scope of the evaluation of the results of the rolling testing of the plurality.

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