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 - 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 - 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 - Mate face/face Mate edge/edge Mate - 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): in translation 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 ... Relationships features Assembly Modeling Components Assembly Component Assembly between components Part /Assembly Modeling Similarities - Part Modeling Assembly Modeling Editing Sketch, feature Part Parametric... 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. ..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