Lecture Autodesk inventor Assembly modeling

Assembly Modeling


Parametric Assembly Modeling
Assembly modeling is used to combine
components to create a 3D parametric
assembly model
A component is either a part or a
subassembly of parts
Essential tool for a work group developing
a product composed of multiple parts
Relatively new (1990’s)
Used extensively in automotive and
aerospace industries


Assembly Modeling Tools
Assembly modeling tools are used to:
Combine components to create
assemblies
Specify location and orientation of
components within an assembly 
constraints


Part/Assembly Modeling Similarities - 1
Part Modeling
Tree
Features 
Structure
Part

Base
Feature
Constraints
Geometric and
Dimensional
Parent/Child between
Relationships features

Assembly Modeling
Components 
Assembly
Component
Assembly
between
components


Part/Assembly Modeling Similarities - 2
Part Modeling

Assembly Modeling

Editing
Sketch, feature Part
Parametric
Local
Global
equations
Documentation Part drawings Assembly drawings

Instancing
Part instances:
Are copies of a part definition
Contain a reference to the part
definition, plus positional
information used to locate the part
Do not significantly increase
assembly file size (one definition,
many positions)
Are useful for standard parts
Are referred to as occurrences in
Inventor


Assembly Constraints
Mate – positions selected faces so that their
surface normals oppose one another, with faces
coincident (or offset). Can also be used for lines
and points
 Flush – positions selected faces flush with one
another (surface normals in same direction),
with faces aligned (or offset)
Angle – positions planar faces at a specific angle
Tangent – positions a curved surface tangent to
another surface
Insert – positions two cylindrical parts so that
their axes are aligned; mate constraint also
applied to two circular edges

Mate - 1
Mate face/face

Mate edge/edge


Mate - 2
Mate point/point

Flush face/face


Tangent
Tangent cylinder/face


Angle
Angle face/face


Insert


Degrees of Freedom
A rigid body has six degrees of
freedom (DOF):



3 in translation
3 in rotation

As assembly constraints are applied, DOF’s are
reduced
Simulation of part motion within an assembly is
possible by properly constraining parts



Zero DOF  part is fixed
Some DOF’s  moving part


Bottom-Up Assembly Design
Define geometry of all parts
Parts placed in assembly file
Position parts using assembly
constraints (e.g., mate, insert)
Whenever possible, constrain parts in
the order in which they would be
assembled in manufacturing
NOTE: Inventor’s adaptive design allows
unconstrained part geometry to be defined
based upon assembly constraints


Top-Down Assembly Design
Begin with design criteria for assembled
product

Parts created within assembly file
Often start with 2D design layout that
captures criteria


Middle-Out Assembly Design
Most assembly modeling employs a
combination of bottom-up and topdown design
Some existing parts brought into
assembly file
Other parts designed directly within the
assembly


Uses of Assembly Models
Measurements between parts
Exploded views
Interference checks
Kinematics analysis
Bill of Materials (BOM) generation
Walk throughs


Assembly Modeling