STEP-NC AP238 STEP Tools, Inc. 14 First Street, Troy, NY (518) / (518) fax Overview of Technical Corrigendum

STEP Tools, Inc. Slide 2© Copyright 2008 — STEP Tools, Inc. What is a Technical Corrigendum? A TC is a small set of change pages that correct issues discovered after publication. –Up to 2 TCs allowed, then must publish a new edition The AP238 TC draft has circulated since April –Addresses issues discovered during past year of testing in Ibusuki, Dallas, Sandviken, and Hartford rounds.

STEP Tools, Inc. Slide 3© Copyright 2008 — STEP Tools, Inc. Corrigendum Contents Current issues addressed by TC –Via points for better High-Speed Machining (HSM) support. –Cross section parameters for Feed Speed optimization. –Touch_probe as a real tool. –Datum and Datum_target reference to workpiece –Using workpieces for In-process geometry –Various grammar fixes and clarifications to the text. Potential items for TC –Curve probing operation –Toolpath placement on Workplan –Simplify rawpiece/finshed piece –Enable/Disable? –others?

STEP Tools, Inc. Slide 4© Copyright 2008 — STEP Tools, Inc. Via Points for HSM Size Reduction High Speed Machining toolpaths use many arcs. –Requires several entities to represent arcs as trimmed curves, (composite curve, composite curve segment, trimmed curve, circle, axis placement, several directions and cartesian points) –This is multiplied over several tool curves (basis, tool axis, surface normal, speed profile) Describe using via points following approach used by STEP kinematics model. –Continue to use polylines with addition of cartesian point subtype via_arc_point. –Subtype for via_helix_point also added. –Previous method can still be used for other types of curve.

STEP Tools, Inc. Slide 5© Copyright 2008 — STEP Tools, Inc. Via Points for HSM Size Reduction Verified by Bordeaux HSM tests in March Measurements for Fishhead HSM Program –Contains part geometry, tolerances and tool paths –Old: 1.9 MB –New: 1 MB For comparison: Mastercam 9 is 3.5 MB G code is MB

STEP Tools, Inc. Slide 6© Copyright 2008 — STEP Tools, Inc. AIM EXPRESS Definitions ENTITY via_arc_point SUBTYPE OF (cartesian_point); WHERE WR1: SIZEOF(USEDIN(SELF, ‘POLYLINE.POINTS')) > 0; WR2: (0 = SIZEOF (QUERY (pl <* USEDIN(SELF, 'POLYLINE.POINTS') | ((pl.points[1] = SELF) OR (pl.points[HiIndex(pl.points)] = SELF)) ))); END_ENTITY; ENTITY via_helix_point SUBTYPE OF (cartesian_point); WHERE WR1: SIZEOF(USEDIN(SELF, 'POLYLINE.POINTS')) > 0; WR2: (0 = SIZEOF (QUERY (pl <* USEDIN(SELF, 'POLYLINE.POINTS') | ((pl.points[1] = SELF) OR (pl.points[HiIndex(pl.points)] = SELF)) ))); END_ENTITY;

STEP Tools, Inc. Slide 7© Copyright 2008 — STEP Tools, Inc. Cross-Section Parameters Add a curve to toolpath that gives a parameterized description of removal cross section at each point. –Tested initial set of parameters in March –Addressed side milling Since March –Parameters for plunge milling have been proposed –Worked on harmonizing the parameters for milling and turning and handling both side and plunge milling. –Adjusted profile origins and parameter defs.

STEP Tools, Inc. Slide 8© Copyright 2008 — STEP Tools, Inc. Cross Section Parameters

STEP Tools, Inc. Slide 9© Copyright 2008 — STEP Tools, Inc. Cross-Section Parameters Current milling turning parameters handled by a bounded curve. –Same structure as tool position, axis, surface normal curves. –Seven dimensions (ADmax, RDmax, Xmaxofs, Ymaxofs, CSArea, XCGofs, YGCofs) ENTITY trajectory ABSTRACT SUPERTYPE OF (ONEOF(cutter_location_trajectory, cutter_contact_trajectory, axis_trajectory)) SUBTYPE OF (toolpath); [... ] cross_section_area_flank_parameters: OPTIONAL bounded_curve; -- ADDED BY TC cross_section_area_plunge_parameters: OPTIONAL bounded_curve; -- ADDED BY TC END_ENTITY;

STEP Tools, Inc. Slide 10© Copyright 2008 — STEP Tools, Inc. Parameters for Turning Cross-Section Origin for Turning Tools –As documented, milling and turning parameters are measured relative to the tool. –Proposal to measure turning parameters relative to the workpiece origin. Parameters measured from workpiece or tool? X Y

STEP Tools, Inc. Slide 11© Copyright 2008 — STEP Tools, Inc. Turning Parameters Origin on workpiece was driven by confusion over a good origin point on the tool –Origin on the tool is still preferred. –Investigate ISO for existing discussion of tool origin –Also see what ISO has to say about origin.

STEP Tools, Inc. Slide 12© Copyright 2008 — STEP Tools, Inc. Parameters for Plunge Milling Plunge milling parameters have been proposed –Use angular values rather than linear Issues –Should they use linear parameters for consistency? –Should these parameters be in a separate optional curve? Coordinate Origin (0, 0) X Y AD max RD max A max offset R max offset Feed (-Z) (step-over direction) Coordinate Origin (0, 0) X Y A CG offset R CG offset Feed (-Z) CG CSA

STEP Tools, Inc. Slide 13© Copyright 2008 — STEP Tools, Inc. Touch Probe as a Real Tool ARM for touch probe changed so that probe is a subtype of tool. –Previously was a stand-alone stub. –Simplifies use because software can handle probes in the same way as other tools. –Enables a connection between a probe and its shape geometry. Previously, there was none. –Change requires minor AIM mapping adjustments to touch_probe and probing operations. –Open to proposal for additional probe characteristics neccesary to operate them effectively. ENTITY touch_probe SUBTYPE OF (machining_tool); -- ADDED BY TC its_id: identifier; END_ENTITY; See curve_probing.txt

STEP Tools, Inc. Slide 14© Copyright 2008 — STEP Tools, Inc. Datum and Datum Target ARM for Datums and Datum Targets changed to add Workpiece reference –Datums and Datum Targets both link to a workpiece at the AIM level, but there is no reference in the ARM model. –Now more in line with features ENTITY Datum ABSTRACT SUPERTYPE; its_workpiece: Workpiece;-- ADDED BY TC END_ENTITY; ENTITY Datum_target; id : STRING; its_workpiece: Workpiece;-- ADDED BY TC END_ENTITY;

STEP Tools, Inc. Slide 15© Copyright 2008 — STEP Tools, Inc. Workpieces for In-process Geometry Change in-process geometry from just shape_rep reference to full workpiece reference –No burden, any shape rep made by a CAD system is already part of a workpiece/product. –Allows in-process to have full range of product properties, such as features and tolerances. –Simplify by moving as-is, to-be, and removal links to supertype »Was three separate sets of properties on Workplan, Machining_workingstep, and Turning_workingstep. »Move up to Executable so it can be used anywhere. ENTITY executable ABSTRACT SUPERTYPE OF (ONEOF( workingstep, nc_function, program_structure)); its_id: identifier; as_is: OPTIONAL Workpiece;-- ADDED BY TC removal: OPTIONAL Workpiece;-- ADDED BY TC to_be: OPTIONAL Workpiece;-- ADDED BY TC END_ENTITY;

STEP Tools, Inc. Slide 16© Copyright 2008 — STEP Tools, Inc. Proposal: Curve Probing Motivation –New devices are becoming available that can measure curves –STEP-NC data contains many bounded curves (tool paths) that can be measured –Applications like the Impeller can be evaluated using bounded curves on the surface 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_curve; as_measured_curve : OPTIONAL bounded_curve; as_measured_normal : OPTIONAL bounded_curve; its_technology: : OPTIONAL technology; path_maximum_deviation : OPTIONAL bounded_curve; -- its_probe?? END_ENTITY See curve_probing.txt

STEP Tools, Inc. Slide 17© Copyright 2008 — STEP Tools, Inc. Proposal: Toolpath Xform on Workplan Motivation –Transform is already possible on individual workingstep –Adding transform to workplan allows more significant reuse. –Transform moves toolpaths from all workingsteps or nested workplans at once. –Could result in a stack of transforms for nested workplans. –Result: ADD ENTITY workplan SUBTYPE OF (program_structure); its_elements: LIST[0:?] OF executable; [...] toolpath_orientation: OPTIONAL axis2_placement_3d; -- ADD? END_ENTITY;

STEP Tools, Inc. Slide 18© Copyright 2008 — STEP Tools, Inc. Proposal: Simplify Raw/Finished Part Motivation –Now that as-is and to-be descriptions are workpieces, what is the difference between »The as-is workpiece of the main workplan and a rawpiece »The to-be workpiece of the main workplan and a finished part? –Can we simplify the rawpiece/finished piece relationship by removing it as a workpiece attribute and using the workplan instead? –Current understanding on next slide.

STEP Tools, Inc. Slide 19© Copyright 2008 — STEP Tools, Inc. Current Scoping Every executable may have an as-is, to-be, delta and fixture model. When an executable is selected the as-is model, to-be model, delta model and fixture model are determined using the following scoping rules: –The models defined for this executable –The model defined for the workplan containing this executable, or the workplan containing that workplan, and so on until the main workplan is found –If no model is found then do not show a model for the as-is, to- be, delta or fixture. Project may have a list of workpieces. These are the pieces produced by the project. A workpiece may have a rawpiece. The rawpiece defines the original starting state (stock) for this workpiece at the beginning of the main workplan.

STEP Tools, Inc. Slide 20© Copyright 2008 — STEP Tools, Inc. Proposed Scoping Main workplan –as-is workpiece describes the state of the material at the start of the workplan (what we have been calling stock) –to-be workpiece describes the state of the material at the end of the workplan (what we have called “workpiece”, finished part, or often just “part”) Any nested workplans or workingsteps –as-is/to-be can be specified to give additional detail/granularity, and give intermediate forms. Project list of workpieces –Workpieces that the project makes (the final deliverables) –May be more than just the to-be of the main workplan because sub workplans may produce finished parts included here. Workpiece “rawpiece” attribute –Initial state of this workpiece before any machining.

STEP Tools, Inc. Slide 21© Copyright 2008 — STEP Tools, Inc. Proposal: Enable/Disable Executable Add an attribute to store the enabled/disabled state of an executable. –Current state is not saved, so everything is enabled whenever you read a file. –Making it part of the model would allow us to put disabled alternates into the file. –Separate issue with Locking executables to disallow any change. ENTITY executable ABSTRACT SUPERTYPE OF (ONEOF( workingstep, nc_function, program_structure)); [... ] enabled: OPTIONAL BOOLEAN;-- ADDED BY TC END_ENTITY;