generative measurement scenario for step-nc iso 10303 ap238 larry maggiano senior systems analyst...

Generative Measurement Scenario for

STEP-NC ISO 10303 AP238

Larry MaggianoSenior Systems Analyst

Mitutoyo America Corporation CTLab1 October 2008

Copyright Mitutoyo America Corp. 2008

AP238 Measurement Scenario

AP238?


Generative Measurement Scenario

• Can AP238 support generative measurement?• AP238 defines four (4) Conformance Classes

– CC1: Probe Points– CC2: CAD Nominal (AP203e1) and Probe Points – CC3: Parametric Measurement via:

• CAD Nominal (AP203e1) and linked Probe Points

– CC4: Generative Measurement via:a) CAD Nominal & GD&T (AP203e2)b)CAD linked Probe Paths


Measurement Scenario

• CC4 STEP Measurement Scenario– STEP with GD&T exists (AP203e2)– STEP with Probe Path doesn’t yet exist

• Scenario Steps1.Create Curve (Probe Path) on CAD model2.Read CAD model and Probe Path3.Generate Measurement Program4.Run Measurement Program


Probe Path for In Process Measurement– Probe points along at 1 mm offset from blade edge– Skip leading and trailing edges


Probe Path for Post Process Measurement

• Scanning CMM follows Curves, not Points• Use same criteria for In Process Measurement

– Scan Curve at 1 mm offset from blade edge– Skip leading and trailing edges

• Create “Curve on Surface” of Impeller Blade– Curve on Surface is CAD Entity, not data point set– Curve is associated with Surface of Blade– Defines precise Scanning Probe Path


Create Curve for Probe Path• Read Impeller (AP203e1) into SolidWorks™• Create 1 mm offset Curves on Surfaces of Blades


Read CAD & Probe Path (~AP238)


Pick Curve for Probe Path


Define Start & End of Probe Path


Define Additional Parameters


Machine Independent ParametersCoordinate System & Datum StructureLabel, Type and Tolerance of FeaturesLabel(s) of Curve(s) on Surfaces(s)• Measurement Precision• Maximum Path Deviation• Start & End Points (or Start & Distance)• Scan Data Pitch

– Include Mapping to discrete Nominal Points• Data output format

– Tip Center or Surface Compensated– Points, Curves, or Both


Machine Dependent Parameters

• Machine & Probe Configurations• Move & Measure Speeds• Approach & Retract Distances• Probe Path Control

– Curvature– Lean– Lead

• Rotary Table Angles • Run In & Run Out• Filtering Algorithms


Generate Measurement Program


Run Measurement Program


Scan Probe Path as an AP238 Entity

• Created by STEP Tools for AP238 TC

ENTITY curve_probing SUBTYPE OF (touch_probing)curve_to_be_measured : bounded_curve;start_position : OPTIONAL axis2_placement_3d;start_direction : OPTIONAL direction;distance : OPTIONAL length_measure;curve_axis : OPTIONAL bounded_curveas_measured_curve : OPTIONAL bounded_curve;as_measured_curve_normal : OPTIONAL bounded_curve;its_technology : OPTIONAL technologypath_maximum_deviation : OPTIONAL bounded_curve;

END_ENTITY;


Scenario Test Results

• Probe Paths can be defined as CAD Curve– Curves are linked to Surfaces and Tolerances– Probe Paths (Curves) can have Parameters

• AP238 can include:– Measurement Plans expressed as:

• Probe Paths (CAD Curves on Surfaces)• Probe Path Parameters (CAD attributes)

• AP238 CC4 Generative Measurement is:– Feasible– Relatively Simple


Next Steps

• Cross-check to: – ISO 16792:2006 (ANSI Y14.41-2003)– Digital Product Definition Data Practices

• Dimensional Metrology Standards Consortium– STEP is a normative DMIS 5.1 Reference– Submit Harmonization SIR – Next meeting is October 27-31, 2008


Thank you!

AP238


generative measurement scenario for step-nc iso 10303 ap238 larry maggiano senior systems analyst...

Documents

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