Gear AT Measurement import enables you to extract gear topology and macro-geometry data from measurement protocol file ( MKA ), out of which one can get a basic set of property files for definition and further adjustments of macroscopic profile data. The basic file set comprises Property file ( CGP ), Definition file ( CGD ) and Measurement file ( CGM ). Figure 144 shows how to access the Import tools.

Results from measurement preprocessing are stored in CGM file. The CGM stores the adjusted data from MKA file in proper format for Gear AT environment. The file names, (CGD ,CGP and CGM ) are derived from input file name, one can edit them if required. All three files ( CGP, CGD and CGM ) are created after hitting "Generate" button automatically from the data and according to boundaries set in the Measure card.

The Gear AT measure file (CGM) can be referenced in the property file (CGP) so it appears in the shape definition Windows. Once the Measure file exists the Measure card is active and provides preview features for the measurement and adjustment of active diameters.

There is a change in dataflow from the measurement file into the Gear AT Solver in this release. In the past releases the CGM file was processed during Gear AT Standard preprocessing and the measurement data was stored in the CGS file, this was a disadvantage as the change in measurement data required new preprocessing run.

The dataflow was improved in the sense that the CGM file is no longer processed in the Gear AT Standard preprocessing, but the measurement data is directly feed into the Gear AT Solver, what makes the measurement data exchange easy and quick. The dataflow comparison is visualized on Figure 145

The measure file can be replaced or added and or removed under modifying of gear element. The data from the measure file are loaded by the Gear AT solver and the measurements are applied at the simulation start once the activity flag in gear element is set.

The Gear AT Measurement Input has following tabs to help you extract and setup gear topology:

 

In the first step all required parameters are extracted from Input file ( MKA ). Outcome of extraction process is displayed in text form and stored as log file. In case some required parameters are not found or cannot be extracted successfully, message about this issue is displayed and default value for given parameter is used. Usually the MKA file contains beside the measurement also basic tooth profile parameters and radial and pitch deviations for each tooth flank.

The MKA file can differ in the way the data is measured, what additional parameters are stored in the header part and finally in language and units used. Most relevant format specific settings are stored in the Header section. The current implementation supports German language and length defined in [mm]. Below the bolted lines are required for adjusting the extraction process. In case UNDEFINED is not present, this value is set to 1000 microns. User can adjust this value later in the dialog box.

HEADER KS.MK.FILE

Following the Header section, gear and measurement parameters are defined, where each parameter in MKA file has unique line key at the line beginning. This enables robust identifications of parameters. Below is the list of required lines:

These parameters are used to construct the basic tooth profile and determine the measurement area.

The import process supports two types of data measurement format. One of the supported formats is a measurement for 1 profile curve typically in the middle of gear width and 1 lead curve typically about middle of the tooth height for each tooth, this format can be further refined by measuring 3 profile curves and 3 lead lines, then also the flank twist can be captured. These two types of measurements are referred as Simple type.
Another type of measurement consist of more the 3 profile curves and typically 1 lead line curve. This format is usually measured just over selected teeth as it is relative time consuming. This type of measurement is referred as Detailed type.
The import detects both types and either both or just one of them can be processed and stored to the Gear AT measure file for later use in simulations.

It is assumed the measurement over tooth profile is done in transversal plane and the measurement points are equidistant in regular roll angle resp. roll length of the gear, see Figure 146. The measurement can be done for multiple teeth. Those teeth measures can be processed after the import into the dialog box.

Usually, the flank measurement is supplemented with pitch and ovality error measures. The error measurement expects formatting as below, here the column Cumulative Pitch Error (Ffp) and Ovality Error (Fr) is important:

In case those measurement blocks are not present in input file, zero deviations are assumed.

The gear basic geometrical parameters can be found in the Parameters tab (Figure 147). Here the thickness definition can be also selected, default is set to backlash free case. There are several measurement types for gear tooth thickness evaluation. Current implementation can process Over ball Measure, and/or Tangent length measurement over given teeth number. At least one of these measures should be available to correctly adjust ideal flank position.

Most of the Parameters are identical with those in General and Tolerance card of Shape Definition dialog box. The ideal profile created based on reduced parameters found in the input file represents just an initial setup for further adjustments of tooth tip and root section in the Shape Definition dialog box. It is strongly recommended to continue import process in Shape Definition dialog box, to setup correct connection of measurement with the ideal flank on both, tip and root sections of tooth.

 

The measurement adjustment and processing can be adjusted on this tab, see (Figure 148).

All detected measure types ( Simple or Detailed ) are listed in the Measure Type menu. The setting is done for both measures individually and both are stored to the Measurement File ( CGM) if selected.
Both measure types can be processed as individual measures for each tooth or averaged measure for single tooth, this depends on available data in the measurement protocol.

Individual processing enables to switch sing of measure and adjusting active diameters for each tooth separately in the Active Diameter Table. The Average processing in addition enables to adjust the measurement offset and as we have only one resulting tooth the active diameters are adjusted in dedicated fields for Average tooth and the Active Diameter Table only lists the detected measures in read only mode.

The Measures are stored in the Measurement File ( CGM) as surface map for each tooth resp, averaged tooth with resolution defined by fields Lead and Profile under Storage Resolution, the default is 50 points over gear width and 150 points over gear over gear height resp over involute contour.
For measurement protocols with more the one Profile measures one can select if the lead measurement is included within the surface map or not, hence for the case the lead measure is not included the lead direction is derived from the fitting over available profile measures defined over gear width. The setting for this feature is available next to the Processing menu.

 

Depending on the Orientation of the Gear in measurement machine and the gear element in model, user can select the Reference Face on the gear model to match the Reference Face on the measurement machine with the Reference Face switch.

The Profiles are measured from gear bottom to gear top face in the measurement machine. The default position is chosen as bottom face is located on the Gear positive side; this corresponds to option Reference Face on negative side. For this setup the tooth flanks are identical on measurement machine and in Gear AT. See Figure 149.

In case the Reference Face is chosen on positive gear side face, the bottom face is on gear negative side and the flanks are interchanged between measurement machine and gear AT. See Figure 150.

The position of the gear bottom face together with Gear AT Datum Face and measured surface can be previewed in form of 3D model, see Figure 151.

The measured data is stored in Measurement file (CGM) transformed to Gear AT gear element coordinate system, meaning first profile is closest one to Gear AT Datum Face. The boundaries of measurement data are defined axially and radially by set of parameters depicted on Figure 152 resp. Figure 153. Those parameters are defined in Gear AT element coordinate system.

 

The Fitting tab enables to preview the raw measurement data and eliminate outlier’s values, perhaps to correct the start and end points on a measurement. In addition, the Fitting spline degree and smoothing parameter can be adjusted for each group of measures: Detailed Profile and Lead measures as well for Simple Profile and Lead measures, see Figure 156.

The points can be skipped as individual points or range of points on single tooth or at range of teeth. Skipped points are not considered in the fitting process. At the same time the fitting spline is used also to extrapolate the measurement until the defined boundary, hence filling the gap for undefined values and or not measured portion of gear flank. The fitted and raw data can be previewed with the Preview Measure 2D button.

 

The measurement informative parameters are listed on this tab, see (Figure 157).

The radial position of measured data points on ideal tooth flank is determined by two parameters. The Start Diameter Data and End Diameter Data define the area on the involute curve, where the given number of measurements is done. Usually, the measurement is equidistant over the Roll Angle, see Figure 158.

Axial position of measured data is determined by two parameters Start Lead Data and End Lead Data, the parameters define where the given amount of measurement is done, usually the measurement is equidistance over the width of the gear.

 

The measurement deviations are listed on this tab, see (Figure 159).

Run out and Pitch Error should supplement the flank measurement. The data is available for left and right flank separately. This data is stored in created cylindrical property file ( CGP ). The Pitch Error measurement is exercise on Measurement Diameter; the data represent length on arc, see Figure 160. From single pitch error (fp) cumulative pitch error can be calculated (Fp). Cumulative pitch error represents relative position of current and ideal flank position. Usually the Runout is calculated from pitch measurement. Both deviations represent the effect on non-uniform locations on gear wheel, only one of their values should be applied, hence pitch error creates runout and vice versa.