Theme III: Process Planning and Validation

Theme Objective:• To develop advanced geometric computing

algorithms and novel closed-loop machining platforms to generate and validate process plans for producing quality machined parts.

Sub-Themes:IIIA. Cutter-Part Engagement Geometry DeterminationIIIB. On-line Process Re-planningIIIC. Off-line Process/Part Validation

Theme IVModular Machine Tool

Controls & Sensors

Theme IIMachine Tool Error Models

Role of Theme III in Overall Network

IIIACutter-Part Engagement Geometry Determination

IIICOff-line Process/Part

Validation

Theme VVirtual Machining

System

Process Plan

Machined Part

IIIBOn-line Process

Re-planning

Theme IMaterials &

Machining Models

Theme III Projects

• Theme Researchers: H.Y. Feng (UBC), P.H. Gu (Calgary), A.D. Spence (McMaster)

• Collaborating Network Researchers: Y. Altintas (UBC), P. Koshy (McMaster)

• Academic Collaborators: R. Fleisig (McMaster), D.Y. Xue (Calgary)

• Industrial Collaborators: F.-É. Delorme, S. Engin (Pratt & Whitney Canada), M. Desnoyer (Origin International), D. McPhail (Memex Automation)

• Four Master’s and four Ph.D. students

IIIA.1: Analytical Formulation of Cutter-Part Engagement from Z-Buffer Images

• Benefits: closed-form solutions accuracy & efficiency

• Proposed Methodology:– Identify the boundary points– Reconstruct the desired piecewise smooth analytical curve

• Current Progress: one MASc to start in September 2011

IIIA.2: Rough / Semi-Finish Machining Optimization

• The originally proposed B-rep (boundary representation) scheme – not robust enough.

• Mesh-based scheme is being explored.

IIIB.1: CNC and Inspection Hardware Integration

• To develop integrated inspection and GD&T decision making at the CNC machine tool

• GD&T processing with Origin software converted to embedded system

• Integration and feedback using Memex CNC control interface

IIIB.2: Modeling and Robust Localization of Free-Form Surfaces

• To develop new modeling techniques & localization methods for precision inspection of free-form surfaces.

• Main feature: considering both the reconstructed curve/surface and its uncertainty at different locations.

Upper tolerance boundary

Lower tolerance boundary

Manufactured curve/surface

Approximated model Variation boundaries

A A

B B B

A

IIIB.3: Measurement Compensated Finish Machining

• To use inspection data to optimize heat treated / cast part finish machining tool paths.

• Tool path generation for compressor blade fillet.

IIIB.4: Surface Comparison and Tool Path Re-planning

• To determine the geometric errors, analyze the errors and develop compensation methods for tool path re-planning.– Determine magnitude and distribution of errors.– Re-program the tool paths to compensate the errors.

IIIC.3: Comprehensive Geometric Error Evaluation of Complex-Shaped Parts

• To fully automate the geometric error evaluation task of complex-shaped machined parts such as compressor, impeller, or turbine blades.

Suction Side Camber Curve

Trailing Edge

Pressure Side

Leading Edge

Suction Side Camber Curve

Trailing Edge

Pressure Side

Leading Edge

Suction Side Camber Curve

Trailing Edge

Pressure Side

Suction Side Camber Curve

Trailing Edge

Pressure Side

Leading Edge

U

Measured Actual

–3σ +3σ

Measured point

Actual curve Feasible curves

Measurement uncertainty circle

Non-linear region

Linear region

IIIC.4: Section-Specific Geometric Error Evaluation via Surface Scanning

• To enable accurate evaluation of geometric errors at specific sections of the machined free-form parts from complete surface scans.

• Current work: scanned noise reduction