Industrial Background Research Problematic Method Overview Key Characteristics Assembly Sequence Conclusion ADCATS Conference - 14/15 June 2001 ADCATS Conference - 14/15 June 2001 Brigham Young University - Provo UT Brigham Young University - Provo UT Benoît Marguet E.A.D.S Corporate Research Center - France Tel : +33-1-46-97-33-46 email : [email protected]Method & Tools for Method & Tools for Geometric Variation Management Geometric Variation Management
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Industrial Background Research Problematic Method Overview Key Characteristics Assembly Sequence Conclusion ADCATS Conference - 14/15 June 2001 Brigham.
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Concepts• Functional requirements & related geometrical characteristics
are too numerous on complex product in order to manage all of them.
• Need to focus attention of designers & manufacturers on what is really
important for the product.
Definition “Product Key Characteristics are the geometrical features of component or sub-component whose variation has the greatest influence on the product function”.
Functional Requirement Identification
(1)
Functional Requirement Identification
(1)
Geometrical Requirement
Identification (2)
Geometrical Requirement
Identification (2)
Product Key Characteristics Identification
(3)
Product Key Characteristics Identification
(3)
Identification Process
KC
1
Product Product Key Characteristics (II)Key Characteristics (II)
Problematic• Various assembly sequences are available for a single product.• All assembly sequence will have a different quality cost for the product.
Question
What assembly sequence will minimize impact of part’s variation on PKCs ?
Assembly Sequence #1
Assembly Sequence #2
Assembly Sequence (II)Assembly Sequence (II)
Concepts• Assembly Sequence analysis focus on PKCs (for variation impact). • Impact of part variation on PKCs depends on assembly sequence
choice.• Selection of assembly sequence is made very early in the design cycle.
Mate & Contact Identification
(1)
Mate & Contact Identification
(1)
Propagation Chain Identification
(2)
Propagation Chain Identification
(2)
Worst Case &StatisticalTolerance Analysis
(3)
Worst Case &StatisticalTolerance Analysis
(3)
Analysis Process
Goal
To analyze as soon as possible during the design cycle, all admissible
assembly sequences in order to select the optimal one.
Mate & Contact Identification (I)
Definition (D.E Whitney) • A mate is an assembly link that establishes constraints and dimensional
relationships between part.• A contact is an assembly link that supports and fastens the part once it
is located.
Property
Mate and Contact are related to the assembly sequence.
Geometrical variations flow from part to part through mates only.
Benefice• Easy to represent on a graph• Tool for variation propagation
analysis.
Assembly Sequence (III)Assembly Sequence (III)
Stringer
Cleat
Cleat Pannel
M
MM
M
MM
C
C
C
C
Mate
Contact
M
C
1
Assembly Sequence (IV)Assembly Sequence (IV)
Assembly Sequence #1
Lower Floor
Lower Shell
Upper Shell Left
Upper Shell Right
Tool
Door
Upper Floor
Mate & Contact Identification (II)
Tools : Assembly Oriented Graph.
Assembly surfaces
Mate
Contact
PKC1
KC
AOG is a directed acyclic graphical representation of an assembly given a picture of the location dependencies of parts and surfaces. Each node represents assembly surface. Oriented arcs represent mates between two assembly surfaces. The arrow points on the positioned component. Oriented dotted arcs represent contacts between two assembly surfaces and dotted line represents geometrical conditions
Need to manage tolerance from the functional requirement to ISO
specification based on :• Product Key Characteristics• Assembly processes• Manufacturing Capabilities
Definition & Deployment of a Variation Management Method• Useful for complex product like aircraft.• Used as soon as possible during the design process.• Allowing to select the optimal assembly sequence.
On going Works • Take into account flexible parts in the method• Automatic assembly sequence planning