METHOD AND DEVICE FOR OPTICAL GEAR MEASUREMENT

Abstract

A method includes the steps providing a component that has toothing with a predetermined nominal geometry; providing a measuring device that has an optical measuring system; and measuring the toothing of the component by the optical measuring system, wherein measuring points are detected. The method further includes the steps of evaluating the measuring points, wherein the evaluation of the measuring points has at least the following steps: grouping the measuring points into flank groups by filtering; modeling profile segments from the measuring points of the flank groups, wherein each flank group is assigned a profile segment; and determining one or more geometric parameters of the toothing on the basis of the profile segments.

Claims

1. A method including, the following steps: providing a component, wherein the component has a toothing with a predetermined nominal geometry; providing a measuring device, wherein the measuring device comprises an optical measuring system; measuring the toothing of the component using the optical measuring system, wherein measuring points are detected; and evaluating measuring points; wherein evaluating of the measuring points includes at least the following steps: grouping of the measuring points into flank groups by filtering; modeling of profile segments from the measuring points of the flank groups, wherein a profile segment is assigned to each flank group; and determining one or more geometric parameters of the toothing on the basis of the profile segments.

2. The method according to claim 1, wherein the grouping of the measuring points into flank groups by filtering includes one or more of the following method steps: radial filtering of the measuring points, wherein a plurality of the measuring points of the flank groups lie between a predetermined minimum radius and a predetermined maximum radius; profile-specific filtering of the measuring points, wherein a plurality of the measuring points of the flank groups are each at a minimum distance from the predetermined nominal geometry of the toothing which does not exceed a predetermined distance; kinematic filtering of the measuring points, wherein a plurality of the measuring points of the flank groups satisfy the condition that, at the time of detection of the respective measuring point, an amount of an acceleration of a machine axis of the measuring device performing a measuring movement is smaller than a predetermined threshold value; and qualitative filtering of the measuring points, wherein a plurality of the measuring points of the flank groups satisfy the condition that during the imaging of a respective measuring point an exposure time does not fall below a predetermined exposure time and/or an intensity does not fall below a predetermined intensity.

3. The method according to claim 1, wherein the grouping of the measuring points into flank groups by filtering comprises one or more of the following test steps: checking whether the number of flank groups corresponds to a double number of teeth of the toothing; checking whether the number of measuring points of a respective flank group exceeds a predetermined minimum number; checking whether the measuring points of a respective flank group have a predetermined distribution; and wherein the test steps are carried out before the modeling.

4. The method according to claim 1, wherein the modeling of profile segments from the measuring points of the flank groups, wherein a profile segment is assigned to each flank group, comprises one of the following method steps: modeling of at least one profile segment as a mathematical non-linear function of higher order, or modeling of several profile segments each as a mathematical nonlinear function of higher order, or modeling of all profile segments each as a mathematical nonlinear function of higher order.

5. The method according to claim, 1 wherein the modeling of profile segments from the measuring points of the flank groups, wherein a profile segment is assigned to each flank group, comprises a plausibility check having one or more of the following method steps: creating a left averaged compensation profile segment from profile segments of left flank groups and checking a deviation of at least one profile segment of a left flank group from the left averaged compensation profile segment; checking a deviation of at least one profile segment of a left flank group from another profile segment of a left flank group; creating a right averaged compensation profile segment from profile segments of right flank groups and checking a deviation of at least one profile segment of a right flank group from the right averaged compensation profile segment; checking a deviation of at least one profile segment of a right flank group from another profile segment of a right flank group; checking a deviation of the left averaged compensation profile segment from the specified nominal geometry; checking a deviation of the right averaged compensation profile segment from the specified nominal geometry; checking a deviation of at least one profile segment from the predetermined nominal geometry and/or from a compensation geometry, wherein the compensation geometry has been determined from the profile segments of the flank groups; and checking a deviation of a first profile segment of a tooth of the toothing of a first measurement from a second profile segment of the same tooth of a second measurement.

6. The method according to claim 5, wherein an adjustment of the filtering and/or an adjustment of a measurement parameter takes place if a deviation exceeds a predefined threshold value.

7. The method according to claim 1, wherein three-dimensional measuring points of at least one flank group, several flank groups or all flank groups are projected into a two-dimensional plane, in before profile segments are created, wherein the modeling of profile segments from the measuring points takes place in the two-dimensional plane as two-dimensional profile segments; or a three-dimensional profile segment of a flank group, three-dimensional profile segments of several flank groups, or three-dimensional profile segments of all flank groups are projected into a two-dimensional plane.

8. The method according to claim 1, wherein a tooth pitch is one of the one or more geometric parameters of the toothing and the tooth pitch is determined on a pitch measuring circle and/or a pitch deviation is one of the one or more geometrical characteristics of the toothing.

9. The method according to claim 1, wherein the component is continuously moved relative to the optical measuring system during the acquisition of the measuring points and/or a focal diameter of the optical measuring system is 50 micrometers or less, and/or the determination of one or more geometric parameters of the toothing on the basis of the profile segments is carried out analogously to the evaluation of a tactile measurement and/or is carried out with an evaluation software for the evaluation of a tactile measurement.

10. A device, having a measuring device, wherein the measuring device comprises an optical measuring system, having a holder for holding a component, having a control and evaluation unit, adapted for carrying out a method including the following steps: providing a component having a toothing with a predetermined nominal geometry; providing the measuring device; measuring the toothing of the component using the optical measuring system, wherein measuring points are detected; and evaluating measuring points including at least the following steps: grouping of the measuring points into flank groups by filtering; modeling of profile segments from the measuring points of the flank groups, wherein a profile segment is assigned to each flank group; and determining one or more geometric parameters of the toothing on the basis of the profile segments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The disclosure is described in more detail below with reference to a drawing illustrating exemplary embodiments. The drawings show schematically in each case:

[0070] FIG. 1A an optical measurement;

[0071] FIG. 1B a tactile measurement;

[0072] FIG. 2A a component to be measured;

[0073] FIG. 2B an optical measurement of the component to be measured from FIG. 2A

[0074] FIG. 3A measuring points of the optical measurement;

[0075] FIG. 3B a magnified view of the measuring points of the optical measurement from FIG. 3A;

[0076] FIG. 3C measuring points of the optical measurement from FIG. 3B before radial filtering;

[0077] FIG. 3D measuring points of the optical measurement from FIG. 3B after radial filtering;

[0078] FIG. 3E measuring points of the optical measurement from FIG. 3D before profile-specific filtering;

[0079] FIG. 3F measuring points of two flank groups of the optical measurement from

[0080] FIG. 3D of the profile-specific filtering;

[0081] FIG. 3G modeled profile segments of two flank groups with the nominal geometry;

[0082] FIG. 3H modeled profile segments in a general overview;

[0083] FIG. 3I modeled profile segments in a general overview with the nominal geometry and a compensation geometry;

[0084] FIG. 3J measuring points of the flank groups of the optical measurement from

[0085] FIG. 3D after radial filtering and after profile-specific filtering in a general overview;

[0086] FIG. 4A a deviation of a left profile segment to a left averaged compensation profile segment;

[0087] FIG. 4B a deviation of a right profile segment to a right averaged compensation profile segment;

[0088] FIG. 4C a deviation of a left profile segment to another left profile segment;

[0089] FIG. 4D a deviation of a right profile segment to another right profile segment;

[0090] FIG. 4E a deviation of a left averaged compensation profile segment from the nominal geometry;

[0091] FIG. 4F a deviation of a right averaged compensation profile segment from the nominal geometry; and

[0092] FIG. 5 a flow chart of the method according to the disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

[0093] FIG. 2A shows a component 2 with a toothing 4. The component 2 is a helical spur gear 2 with an involute toothing 4. The tooth pitch of the toothing 4 is to be measured on the helical spur gear 2. For this purpose, a flank line section 8 on a left flank 10 and a flank line section 12 on a right flank 14 are to be measured on each tooth 6 of the toothing 4. Exemplarily, a flank line section 8 on a left flank 10 and a flank line section 12 on a right flank 14 of two adjacent teeth 6 are shown.

[0094] The spur gear 4 is measured by means of a measuring device 16, which has an optical measuring system 18 (step (I)). During the measurement, the spur gear 2 rotates continuously about its own axis, which can in particular be aligned collinearly to the z-axis of the Cartesian coordinate system x-y-z. It will be understood that any other Cartesian coordinate system or polar coordinate system may also be used.

[0095] In addition to the rotation about the z-axis, a linear relative movement takes place in the z-direction, resulting in the measuring path indicated by the dashed lines, which covers the flank line sections 8, 12 of all teeth 6 to be measured. Thereby, the optical measuring system 18 measures the complete tooth profiles, including the tooth tip, the tooth flank and the tooth root of each tooth.

[0096] A plurality of measuring points 20 are therefore acquired, wherein the measuring points 20 are shown in FIG. 3A for a view in traverse section. FIG. 3B shows an enlarged view of measuring points 20 of a tooth in traverse section, wherein a section of a predetermined nominal geometry 22 of the toothing 4 is shown in the form of a profile line 22. Each individual measuring point 24 of the plurality of measuring points 20 is defined by an x-value, a y-value and a z-value, i.e. its position in space according to the Cartesian coordinate system x-y-z.

[0097] In a next step, the measuring points 20 are grouped into flank groups 26 by filtering (step (II)).

[0098] FIGS. 3C and 3D illustrate a radial filtering of the measuring points 20, wherein all measuring points 20 of the flank groups 26 are located between a predetermined circle R.sub.MIN having a minimum radius and a predetermined circle R.sub.MAX having a maximum radius. The radius of the circle R.sub.MIN is larger than a radius of the root circle FK of the toothing 4. The radius of the circle R.sub.MAX is smaller than a radius of the tip circle KK of the toothing 4. Further, the pitch circle TK is drawn.

[0099] If the radial filter shown in FIG. 3C is applied to the measuring points, all measuring points outside the filter band bounded by R.sub.MIN and R.sub.MAX are sorted out or masked out or deleted. The measuring points 20 remaining after radial filtering are shown in FIG. 3D. For better clarity, those areas of the nominal profile 22 which do not lie between R.sub.MIN and R.sub.MAX are now also masked out.

[0100] This radial filtering already defines the number of flank groups 26, which may also be referred to as contiguous measuring sections 26. The result of the radial filtering is further illustrated in FIG. 3J, which shows the flank groups 26 for all teeth 6 of the toothing 4, wherein only two flank groups 26 have been provided with a reference sign.

[0101] It is now checked whether the number of flank groups 26 corresponds to twice the number of teeth of the toothing 4, wherein the number of teeth here are equal to 18 (step (III)). In the present case, the check shows that the number of flank groups 26 corresponds to twice the number of teeth, since 36 flank groups have been generated. Therefore, the radial filtering check is positive and the radial filtering does not need to be adjusted. Each individual left flank and each individual right flank of the toothing is therefore associated with one flank group 26 and one contiguous measuring section 26 respectively.

[0102] It is further checked whether each of the respective flank groups has a sufficient number of measuring points and whether these measuring points of a respective flank group are sufficiently evenly distributed (step (III)).

[0103] In a next step, a profile-specific filtering is performed, wherein all measuring points 20 of a respective flank group 26 have a respective minimum distance to the predetermined nominal geometry 22 of the toothing 4 which does not exceed a predetermined distance. This means that each of the flank groups 26 is filtered again, as will be described with reference to FIGS. 3E and 3F below (step (IV)).

[0104] For each flank group 26, according to FIGS. 3E and 3F, those measuring points 20 are sorted out or masked out or deleted that do not lie within a band bounded by lines P+ and P−, wherein P+ and P− are substantially offset profile lines of the target profile. FIG. 3F shows the flank groups 26 after applying the profile-specific filtering.

[0105] Furthermore, a kinematic filtering of the measuring points 20 is performed, wherein all measuring points 20 of the flank groups 26 satisfy the condition that at the time of detection of the respective measuring point 20 an amount of an acceleration of a machine axis A of the measuring device 16 performing a measuring movement is smaller than a predetermined threshold value, wherein the machine axis A is a spindle axis A performing the rotation, which spindle axis A is extended along the z-axis and carries the component 2 (step (IV)).

[0106] In addition, qualitative filtering of the measuring points 20 is performed, wherein all of the measuring points 20 of the flank groups 26 satisfy the condition of not falling below a predetermined exposure time and/or a predetermined intensity during the imaging of a respective measuring point 24 (step (IV)).

[0107] For each flank group 26, a profile segment 28, 30 is then modeled in each case as a mathematical non-linear function of higher order, wherein profile segments of left flanks 10 are designated as profile segments 28 and profile segments of right flanks 14 are designated as profile segments 30 (FIG. 3G, FIG. 3H). In the manner described above, the profile segments 28, 30 can be created for each height z in order to represent the measured tooth flanks (step (V)).

[0108] Alternatively or additionally, it can be provided that the three-dimensionally defined measuring points of all flank groups are projected into a two-dimensional plane before filtering, wherein the modeling of profile segments from the measuring points in the two-dimensional plane takes place as two-dimensional profile segments. By projecting the measuring points onto the two-dimensional plane along the flank line, averaging can be performed according to tactile measurement.

[0109] The determination of one or more geometric parameters of the toothing on the basis of the profile segments 28, 30 can be carried out analogously to the evaluation of a tactile measurement and, in particular, can be carried out by means of evaluation software for evaluating a tactile measurement in order to determine the tooth pitch on the basis of the flank lines 8, 12 and other geometric parameters of the toothing (step (VI)).

[0110] Alternatively or additionally, a respective flank line 8, 12 may be directly generated by filtering and modeling using the aforementioned method.

[0111] Prior to the evaluation and determination of geometric parameters of the toothing, a plausibility check of the modeled profile segments can be performed, using one or more of the following method steps:

[0112] Creating a left averaged compensation profile segment 280 from profile segments 28 of left flank groups 26, and checking a deviation of at least one profile segment 28 of a left flank group 26 from the left averaged compensation profile segment 280 (FIG. 4A).

[0113] Creating a right averaged compensation profile segment 300 from profile segments 30 of right flank groups 26, and checking a deviation of at least one profile segment 30 of a right flank group 26 from the right averaged compensation profile segment 300 (FIG. 4B).

[0114] Checking a deviation of at least one profile segment 28 of a left flank group 26 from another profile segment 28 of a left flank group 28 (FIG. 4C).

[0115] Checking a deviation of at least one profile segment 30 of a right flank group 26 from another profile segment 30 of a right flank group 26 (FIG. 4D).

[0116] Checking a deviation of the left averaged compensation profile segment 280 from the predetermined nominal geometry and checking a deviation of the right averaged compensation profile segment 300 from the predetermined nominal geometry (FIG. 4E; FIG. 4F).

[0117] Checking a deviation of at least one profile segment 28, 30 from the predetermined nominal geometry 22 and/or from a compensation geometry 400, wherein the compensation geometry 400 has been determined from the profile segments 28, 20 of the flank groups 26 (FIG. 3I). In the schematic representation of FIG. 3I, the nominal geometry 22 and the compensation geometry 400 are drawn congruent, although in reality they are not exactly congruent.