Lecture Autodesk inventor Assembly modeling

In this chapter you learn how to use more advanced features for modeling in the assembly environment, learn how to minimize the impact of file size for large assemblies, learn how to create weldments and assemblylevelonly features, learn how to work more effectively in the assembly environment.

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 Assembly Modeling Tree

Structure Features  Part Components  Assembly

Base Feature Component

Constraints Geometric and

Dimensional Assembly Parent/Child

Relationships between features between components

Part/Assembly Modeling Similarities - 2

Part Modeling Assembly Modeling Editing Sketch, feature Part

Parametric

equations Local Global

Documentation Part drawings Assembly drawings

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

Part instances:

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 cylinder/face

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

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

top-down 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