Setup of rolling test for spur gear

Abstract

To provide a method which enables a robust and reliable rolling test of spur gears and, in particular, reduces the overall testing effort.SOLUTION: A method includes the steps of: hard finishing a plurality of spur gears, each gear of each spur gear being hard-finished; performing rolling test of hard-finished spur gears by a rolling test rig for which standard deviation has been determined; performing end-of-line testing of the hard-finished spur gears by a gear test rig; and performing evaluation of the end-of-line test results of the hard-finished spur gears, the spur gears being declared as non-defective or defective based on at least one quality criterion, the results of the rolling test each comprising an order analysis, and a tolerance limit being determined for one or more orders in each case.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rolling test method for gears, and in particular to a rolling test setup for the serial production of spur tooth profiles or spur gears. [Background technology]

[0002] Due to the increasing importance of the noise behavior of vehicle transmissions, spur gears are also increasingly subjected to rolling or end-of-line tests, which check the dynamic behavior, and in particular the noise behavior, of the associated spur gears. Corresponding manufacturing processes and quality control loops are known, for example, from document WO2022207371A1. Summary of the Invention [Problem to be solved by the invention]

[0003] The production of spur gears presents the problem that the rolling test tolerances are not known in advance, so setting up rolling tests for series production of spur gears is complex and often can only be carried out by experienced or specially trained personnel.

[0004] Against this background, the technical problem of the present invention is to identify a method that enables robust and reliable rolling tests of spur gears, and in particular, reduces the overall testing effort. [Means for solving the problem]

[0005] The above-mentioned technical problem is solved by the features of the independent claims. Further designs of the invention can be derived from the dependent claims and the following description.

[0006] The present invention relates to a method, comprising the method steps of rolling-testing spur gears with a rolling test rig, the results of which are statistically checked for repeatability and reproducibility and a standard deviation of the rolling test results is determined; hardened and finished a plurality of spur gears, the tooth profiles of each of which are hardened and finished; rolling-testing the hardened and finished spur gears with the rolling test rig for which the standard deviation has been determined; and hardened and finished spur gears with the gear test rig for which the standard deviation has been determined. The method therefore comprises the method steps of performing an end-of-line test, evaluating the results of the end-of-line test of a plurality of hardened and finished gears, in which the spur gears are declared as good or bad on the basis of at least one quality criterion, and evaluating the results of a rolling test of a plurality of hardened and finished spur gears, in which the tests of the spur gears are evaluated to be declared as good according to the end-of-line test, the results of the rolling test comprising an order analysis, in each case determining tolerance limits for one or more orders.

[0007] According to the invention, the end-of-line test therefore forms the basis for defining good and bad products, and one or more order-specific tolerance limits are defined for the rolling test by using the rolling test results of spur gears declared as good in the end-of-line test.

[0008] For example, end of line testing may be used to determine one or more order-specific tolerance limits for rolling tests by comparing the results of the end of line test with the results of the rolling tests.

[0009] Thus, the tolerances of the rolling test can be determined and set by the process sequence defined in accordance with the present invention.

[0010] In this way, reliable and robust rolling tests of spur gears can be carried out.

[0011] The rolling test may preferably be a single flank rolling test. Alternatively, the rolling test may be a double flank rolling test.

[0012] The rolling test rig for rolling tests and the gear test rig for end-of-line tests are two separate and distinct devices. In the rolling test, the spur gear to be tested rolls together with a master gear in a known manner, for example to measure rotational errors or similar deviations. The end-of-line test concerns an acoustic test of each spur gear to be tested fully assembled in the gearbox housing. That is, the tooth profile to be tested is tested in the end-of-line test rig together with the adjacent spur gear with corresponding surrounding bearings, or in the gearset pair intended for use, according to the actual installation situation. In particular, fully assembled gearboxes intended for delivery can be tested on the test rig using the end-of-line test.

[0013] Each spur gear may be an externally toothed spur gear.

[0014] Each spur gear may have a spur tooth profile. Alternatively, each spur gear may have a helical tooth profile.

[0015] Each tooth profile of each spur gear may have modifications such as crowning, retraction, etc.

[0016] In the method according to the present invention, the repeatability and reproducibility of the rolling test are first checked. This test, also known as a "gauge R&R" test, is a technical term that refers to testing the capability of a specific measurement system for a specific measurement task. In particular, it is tested whether the combination of the rolling test rig with the master wheel used and the clamp intended for the tooth profile being tested produces reproducible and repeatable results. For example, defects or wear in the rolling test rig or parts of the rolling test rig, the master wheel, or the clamp can cause significant variations in the results of the rolling test or even random results. In this case, the test setup must be modified until repeatability and reproducibility are guaranteed.

[0017] During the rolling test, the spur gear used to check repeatability and reproducibility rolls with the same or identical master gear as the master gear also used for the rolling test in series production, and therefore the spur gear used for the repeatability and reproducibility check is based on the same nominal geometry as the further spur gear.

[0018] Finishing of spur gears after hardening can be carried out, for example, by grinding processes, which can be continuous indexing grinding processes such as generating grinding with a grinding worm, or single indexing grinding processes such as profile grinding or generating grinding with a grinding wheel.

[0019] Each spur gear is hardened and then quenched before being finish machined.

[0020] The testing of each spur gear in an end-of-line test is a test of its acoustic behavior. Quality criteria for such end-of-line noise tests include, for example, sound pressure level, airborne noise, structure-borne noise, volume level, and transmitted noise loudness, as well as tonality, i.e., the degree to which the dominant frequencies of the transmitted noise are prominent and perceptible as individual sounds. A well-known analysis of noise behavior using end-of-line tests is the so-called NVH criteria, where the abbreviation NVH stands for "noise," "vibration," and "harshness." For example, end-of-line tests for one or each of the aforementioned noise evaluation characteristics may have limit values ​​that a spur gear must meet to be declared good.

[0021] Order analysis presents the results of the rolling test as an order spectrum, where individual orders and / or order ranges of the order spectrum may be assigned test characteristics of the tooth profile, such as concentricity error, wobble, first order and / or higher order pitch error, surface waviness, flank form error, etc.

[0022] The results of rolling tests are generated by providing rotation-related shaft data, specifically from a rolling test rig, as an order spectrum using an FFT. The abbreviation FFT stands for Fast Fourier Transform. Since an order is a multiple of the speed of the spur gear on the rolling test rig, the measured deviation or reading is plotted as amplitude across each individual order.

[0023] End-of-line testing and the application of NVH criteria, as well as the evaluation of other acoustic characteristics as part of end-of-line testing, are prior art and well known. This equally applies to rolling tests and the associated order analysis. The present invention is to use end-of-line testing to determine tolerances for rolling tests based on good parts from end-of-line testing, thereby simplifying the rolling test setup.

[0024] Therefore, spur gears declared good in end-of-line testing are used as a basis for defining tolerances for multiple orders used in rolling tests in serial production.

[0025] For example, it is possible to analyze which of three spur gears declared good in end-of-line testing has the largest amplitude of the first order of the rolling test in the rolling test. The average value of these amplitudes can be defined as the tolerance limit for the first order, and compliance with this tolerance limit can be checked during rolling tests of further spur gears in series production. Alternatively, the maximum value of the amplitude of a particular order can be determined and defined as the tolerance limit for this order. Again, only parts that have been declared good in end-of-line testing are used as the reference.

[0026] During the rolling test setup, the post-hardening finishing, rolling test, and end-of-line test for different spur gears can be performed at least partially simultaneously. The order of the rolling test and end-of-line test is optional during the rolling test setup, with the rolling test of the related spur gear preferably being performed before the end-of-line test.

[0027] The steps described above describe the setup of the rolling test and the comparison of the rolling test with the end-of-line test, the actual series production of which will be referred to below as the post-hardening finishing of the "further spur gears". For these further spur gears or corresponding production batches, the rolling test set up in this way is therefore used as part of the rolling test to check the quality of the further spur gears against the specified tolerances.

[0028] Thus, after setting up the rolling test, it is possible to perform post-hardening finish machining of the further spur gears and rolling tests on the further spur gears, the results of the rolling test of each further spur gear including a respective order analysis, and checking compliance with respective specified tolerance limits for one or more orders of each order analysis.

[0029] It may be provided that an end-of-line test is carried out for each further spur gear for which the defined tolerance limits are not met, i.e. spur gears which do not meet the defined tolerance limits during the rolling test, i.e. which are declared defective according to the rolling test, can be sent to an end-of-line test for adjustment.

[0030] The end of line test will indicate for this spur gear either that the rolling test results are accurate, that the spur gear is in fact defective, or that the rolling test may be inaccurate and the spur gear will be declared good according to the end of line test, and the rolling test tolerance limits may be adjusted as necessary. In this way, a quality control loop for the rolling test can be created by periodically comparing the rolling test with the end of line test to achieve the best possible correlation between the two.

[0031] It may be provided that the tolerance limits of the orders that have not been reached for the further spur gear according to the order analysis of the rolling test are adjusted if end-of-line testing of the further spur gear indicates that the further spur gear should be declared good according to the quality criteria of the end-of-line testing.

[0032] In particular, the procedure according to the invention allows the extent of end-of-line testing to be reduced: if a good correlation is achieved between the rolling test and the end-of-line test, it is not necessary to subject all spur gears to end-of-line testing, since the results of the rolling test are sufficiently predictive of the results of the end-of-line test. In particular, it can therefore be provided that each further spur gear for which the defined tolerance limits are met is not subjected to end-of-line testing.

[0033] Alternatively or additionally, in order to check the correlation between the rolling test and the end-of-line test, it may be provided that the individual spur gears are subjected to an end-of-line test, either randomly or at regular intervals or after a predetermined number of manufactured parts, regardless of the results of the rolling test.

[0034] It should be noted that the rolling test may be performed on 100% of the additional spur gears. That is, all additional spur gears are subjected to the rolling test. However, due to the correlation between the rolling test and the end-of-line test, it is not necessary for all spur gears to also be subjected to the end-of-line test. Rather, according to the present invention, only a subset of the additional spur gears are subjected to the end-of-line test. Therefore, the number of additional spur gears subjected to the rolling test is greater than the number of additional spur gears subjected to the end-of-line test. In this way, the test time can be significantly reduced.

[0035] As previously mentioned, even after the rolling test has been set up with the end-of-line test, further monitoring and adjustment of one or more tolerance limits may be performed to improve or permanently ensure correlation between the rolling test and the end-of-line test. [Brief explanation of the drawings]

[0036] The invention will be explained in more detail below with reference to the drawings which show exemplary embodiments, each case being shown diagrammatically. [Figure 1] FIG. 1 shows steps of the method according to the present invention. [Figure 2] Gear cutting machine. [Figure 3] Generating grinding of spur gears. [Figure 4] Apparatus for single flank rolling tests. [Figure 5] Apparatus for double flank rolling tests. [Figure 6] Line termination test. DETAILED DESCRIPTION OF THE INVENTION

[0037] In method step (A), first, a rolling test of the spur gear is performed by a rolling test rig, and the results of the rolling test are statistically checked for repeatability and reproducibility to determine the standard deviation for the results of the rolling test.

[0038] The results are conceptually shown in Figure 1 (A) below, where an order spectrum of the rotation error is constructed and each order is assigned a standard deviation in the form of error bars F.

[0039] Subsequently, according to step (B), a hardened finish is performed on the plurality of spur gears, in which each tooth profile of each spur gear is hardened and finished, and a rolling test of the hardened and finished plurality of spur gears is performed using the rolling test rig for which the standard deviation has been determined. Further, an end-of-line test is performed on the plurality of hardened and finished spur gears using the gear test rig, and the results of the end-of-line test of the plurality of hardened and finished spur gears are evaluated and the spur gears are declared as good or bad based on a quality criterion, which may be, for example, a known NVH rating or an NVH criterion from the end-of-line test.

[0040] Figure 1 (B) shows the results of rolling tests on several hardened and finish-machined spur gears as an order analysis of the spur gears that were declared good in the end-of-line test.

[0041] The maximum value of each order from (B) and the standard deviation from (A) are used to define the tolerance T for each order of the rolling test. The determination of the tolerance is shown in Figure 1 according to diagram (C). Thus, for each order under consideration, it is checked which of the hardened and finished spur gears declared good according to the end-of-line test form the maximum deviation for a certain order, and this deviation is defined as the tolerance limit for each order.

[0042] Thus, according to step (C), the setup for the rolling test is first completed, post-hardening finish machining of the further spur gears may be performed, and the rolling tests of the further spur gears may be performed, the results of the rolling tests of each further spur gear respectively including order analyses, and compliance with the respective tolerance limits determined according to step (C) is checked for one or more orders in each order analysis.

[0043] For further spur gears that do not meet the tolerance limits defined in step (C), an end-of-line test can be carried out. If, in contrast to the rolling test, the end-of-line test shows that the spur gear is good, the corresponding tolerance limit of the rolling test can be adjusted with the amplitude of the relevant order using this spur gear as the new corrected tolerance limit TK for subsequent rolling tests. This procedure is illustrated in Figure 1 under step (D).

[0044] Therefore, in step (D), it is found that TK exceeds the originally defined tolerance limit T. Therefore, the tolerance limit T is raised to the value TK of the corresponding order.

[0045] In other words, following the order analysis of the rolling test, the tolerance limits of the orders that were not achieved for the further spur gear are adjusted if the end-of-line test of the further spur gear indicates that the further spur gear should be declared good according to the quality criteria of the end-of-line test.

[0046] Thus, the end-of-line test constitutes a standard, whereby the tolerances of the order of the rolling test are adjusted based on the end-of-line test to achieve the best possible correlation between the rolling test and the end-of-line test.

[0047] Figure 2 shows a gear cutting machine 2 for hardening spur gears, i.e., a gear grinding machine 2. The gear grinding machine 2 has a tool spindle 4 for holding and rotating a grinding tool. The gear grinding machine 2 has a workpiece spindle 6 for holding and rotating a spur gear with teeth to be ground. The gear grinding machine 2 has a dressing device 8 for dressing the grinding tool.

[0048] The gear grinding machine 2 has numerically controlled machine axes X, Y, Z, A, B, C, C2, B2 for performing relative translational and rotational movements to provide the machining movements required during cutting or dressing of the gear. Additionally, the gear grinding machine 2 has an axis Z1 with a movable quill 12 for clamping a shaft or mandrel.

[0049] FIG. 3 shows a schematic example of a tool spindle 4 holding a dressable grinding worm 14 and a workpiece spindle 6 holding a toothed spur gear 16, the workpiece being ground, the teeth of which are to be ground.

[0050] FIG. 4 shows an example of the general construction of a test rig 28 for performing single flank rolling tests on each spur gear 16.

[0051] The test rig 28 includes a first drive 30 and a second drive 32. The first drive 30 is arranged to drive a first shaft 34 on which the toothed spur gear 16 to be tested is mounted.

[0052] The second drive 32 serves to brake a mating gear 36 mounted on a second shaft 38 coupled to the second drive 32 .

[0053] The mating gear 36 is an externally toothed spur gear, or master gear, that meshes with the tooth profile of the spur gear 16. By simultaneously driving the spur gear 16 and braking the mating gear 36, the speed and torque during the test run can be set. It is understood that the speed and torque curves can also be adjusted. The center distance a1 between the shafts 38, 34 is constant.

[0054] The test rig 28 includes a rotary encoder or angle measurement system 40 , a rotational acceleration sensor 42 , and a structure-borne sound sensor 44 .

[0055] Alternatively or additionally, a two-flank rolling test can be performed. A test rig 46 for a double-flank rolling test is shown diagrammatically by way of example in Figure 5. To avoid repetition, the same features are assigned the same reference numerals in the following.

[0056] The double flank rolling test is essentially different from the single flank rolling test described above with reference to Figure 4 in that the center distance a2 is not constant during the test. The mating gear 36 is mounted on and supported by a movable carriage 48 together with its shaft 38. The movable carriage 48 is supported by a spring device 50 on a stationary counter holder 52.

[0057] The spring device 50 urges the mating gear 36 into tooth contact with the tooth profile of the spur gear 16 under test, with both the right and left flanks of the tooth profile of the spur gear 16 under test making contact on both sides of the tooth contact.

[0058] During the test, i.e. while the toothed spur gear 16 and the mating gear 36 are rolling, the mating gear 36 is pressed in the direction of the spur gear 16 with a defined force.

[0059] The deviation is detected by translational displacement of the movable carriage 34, whereupon a displacement transducer 54 and a vibration transducer 56 are associated with the carriage 48 to record the measurement data. The single flank rolling test and the double flank rolling test are prior art.

[0060] Figure 6 shows an end-of-line test rig 58 in which a spur gear 16 to be tested is mounted in a gear housing 60 and mated with a mating gear 62 to be shipped. Acoustic testing is performed, i.e., an analysis of the transmitted noise with respect to one or more quality criteria is performed. End of line testing is prior art.

Claims

1. a method step of rolling test of a spur gear (16) by means of a rolling test rig (28, 46), wherein the results of said rolling test are statistically checked for repeatability and reproducibility and the standard deviation of the results of said rolling test is determined; A method of post-hardening finishing a plurality of spur gears (16), wherein each tooth profile (17) of each spur gear (16) is post-hardened and finished; a rolling test of the plurality of hardened and finished spur gears (16) by means of a rolling test rig (28, 46) for which a standard deviation has been determined; the method steps of end-of-line testing of the plurality of hardened and finished spur gears (16) by a gear testing rig (58); a method step of evaluating the results of the end-of-line test of the plurality of hardened and finished spur gears (16), wherein the spur gears (16) are declared good or bad based on at least one quality criterion; a method step of evaluating the results of the rolling test of the plurality of hardened and finished spur gears (16), the results of which are evaluated to determine which are declared good according to the end-of-line test, the results of the rolling test each including an order analysis, in each case determining tolerance limits for one or more orders; A method comprising:

2. After the evaluation of the results of the rolling test of the plurality of hardened and finished spur gears (16), further hardened and finished spur gears (16) are subjected to rolling tests, the results of the rolling test of each further spur gear including a respective order analysis, and one or more orders of each order analysis are checked for compliance with respective defined tolerance limits (T). The method of claim 1.

3. Each of said further spur gears (16) for which the defined tolerance limit (T) is not observed is subjected to an end-of-line test. The method of claim 2.

4. According to the order analysis of the rolling test, the tolerance limits (T) of the orders not met for the further spur gear (16) are adjusted if the end-of-line test of the further spur gear (16) indicates that according to quality standards the further spur gear (16) should be declared good. The method of claim 3.

5. Each of the further spur gears (16) for which the defined tolerance limits are met is not subjected to an end-of-line test.

5. The method according to any one of claims 1 to 4.

6. All the further spur gears (16) are subjected to the rolling test.

6. The method according to any one of claims 1 to 5.

7. One or more tolerance limits (T) are monitored and adjusted to improve correlation between the rolling test and the end-of-line test.

7. The method according to any one of claims 1 to 6.

8. The rolling test is a single flank rolling test and / or a double flank rolling test; 8. The method according to any one of claims 1 to 7.

9. Each spur gear (16) to be tested for the end-of-line test is mounted in a gearbox housing (60), the gearbox housing (60) reflecting the mounting of the spur gear (16) according to the operating conditions in the delivery state of the completed gearbox, or the gearbox housing is the gearbox housing of the gearbox as delivered.

9. The method according to any one of claims 1 to 8.

10. As part of the evaluation of the results of a plurality of the rolling tests, the maximum deviation of an order is defined as an acceptable limit for this order.

10. The method according to any one of claims 1 to 9.

Images