NX 12 for Engineering Design - Computer Aided Design Theory

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NX 12 for Engineering Design - Computer Aided Design Theory

Transcript Of NX 12 for Engineering Design - Computer Aided Design Theory

NX 12 for Engineering Design

Contents
PREFACE ................................................................................................................. 1
CHAPTER 1 – INTRODUCTION.........................................................................2
1.1 PRODUCT REALIZATION PROCESS ..............................................................................2 1.2 BRIEF HISTORY OF CAD/CAM DEVELOPMENT.........................................................3 1.3 DEFINITION OF CAD/CAM/CAE .....................................................................................5
1.3.1 Computer Aided Design – CAD .................................................................................. 5 1.3.2 Computer Aided Manufacturing – CAM ..................................................................... 5 1.3.3 Computer Aided Engineering – CAE........................................................................... 5 1.4. SCOPE OF THIS TUTORIAL ............................................................................................6
CHAPTER 2 – GETTING STARTED ..................................................................8
2.1 STARTING AN NX 12 SESSION AND OPENING FILES ...............................................8 2.1.1 Start an NX 12 Session................................................................................................. 8 2.1.2 Open a New File........................................................................................................... 9 2.1.3 Open a Part File .......................................................................................................... 10
2.2 PRINTING, SAVING AND CLOSING FILES .................................................................12 2.2.1 Print an NX 12 Image................................................................................................. 12 2.2.2 Save Part Files ............................................................................................................ 12 2.2.3 Close Part Files........................................................................................................... 13 2.2.4 Exit an NX 12 Session ............................................................................................... 14
2.3 NX 12 INTERFACE ...........................................................................................................14 2.3.1 Mouse Functionality................................................................................................... 14 2.3.2 NX 12 Gateway .......................................................................................................... 17 2.3.3 Geometry Selection .................................................................................................... 21 2.3.4 User Preferences......................................................................................................... 22 2.3.5 Applications ............................................................................................................... 25
2.4 LAYERS .............................................................................................................................26 2.4.1 Layer Control ............................................................................................................. 26
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2.4.2 Commands in Layers.................................................................................................. 27 2.5 COORDINATE SYSTEMS................................................................................................29
2.5.1 Absolute Coordinate System ...................................................................................... 29 2.5.2 Work Coordinate System ........................................................................................... 29 2.5.3 Moving the WCS........................................................................................................ 29 2.6 TOOLBARS........................................................................................................................30
CHAPTER 3 – TWO DIMENSIONAL SKETCHING......................................33
3.1 OVERVIEW .......................................................................................................................33 3.2 SKETCHING ENVIRONMENT........................................................................................34 3.3 SKETCH CURVE TOOLBAR...........................................................................................35 3.4 CONSTRAINTS TOOLBAR .............................................................................................37 3.5 EXAMPLES........................................................................................................................40
3.5.1 Arbor Press Base ........................................................................................................ 40 3.5.2 Impeller Lower Casing ............................................................................................... 44 3.5.3 Impeller ...................................................................................................................... 48 3.6 EXERCISES .......................................................................................................................50 3.6.1 Circular Base .............................................................................................................. 50 3.6.2 Sketching of a Holder................................................................................................. 50
CHAPTER 4 – THREE DIMENSIONAL MODELING ...................................51
4.1 TYPES OF FEATURES .....................................................................................................51 4.1.1 Primitives ................................................................................................................... 52 4.1.2 Reference Features ..................................................................................................... 52 4.1.3 Swept Features ........................................................................................................... 53 4.1.4 Remove Features ........................................................................................................ 54 4.1.5 Extract Features .......................................................................................................... 54 4.1.6 User-Defined features ................................................................................................ 55
4.2 PRIMITIVES ......................................................................................................................55 4.2.1 Model a Block ............................................................................................................ 55 4.2.2 Model a Shaft ............................................................................................................. 57 II

4.3 REFERENCE FEATURES.................................................................................................60 4.3.1 Datum Plane ............................................................................................................... 60 4.3.2 Datum Axis ................................................................................................................ 61
4.4 SWEPT FEATURES ..........................................................................................................62 4.5 REMOVE FEATURES.......................................................................................................67
4.5.1 General Hole .............................................................................................................. 67 4.5.2 Pocket ......................................................................................................................... 69 4.5.3 Slot ............................................................................................................................. 70 4.5.4 Groove ........................................................................................................................ 70 4.6 FEATURE OPERATIONS .................................................................................................70 4.6.1 Edge Blend ................................................................................................................. 70 4.6.2 Chamfer ...................................................................................................................... 71 4.6.3 Thread......................................................................................................................... 71 4.6.4 Trim Body .................................................................................................................. 72 4.6.5 Split Body................................................................................................................... 73 4.6.6 Mirror ......................................................................................................................... 73 4.6.7 Pattern......................................................................................................................... 73 4.6.8 Boolean Operations .................................................................................................... 74 4.6.9 Move........................................................................................................................... 75 4.7 EXAMPLES........................................................................................................................77 4.7.1 Hexagonal Screw........................................................................................................ 77 4.7.2 Hexagonal Nut............................................................................................................ 80 4.7.3 L-Bar .......................................................................................................................... 83 4.7.4 Rack............................................................................................................................ 87 4.7.5 Impeller ...................................................................................................................... 92 4.8 STANDARD PARTS LIBRARY .......................................................................................95 4.9 SYNCHRONOUS TECHNOLOGY ..................................................................................96 4.10 EXERCISES ...................................................................................................................100 4.10.1 Rocker Arm ............................................................................................................ 100 4.10.2 Holder ..................................................................................................................... 100
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4.10.3 Impeller Upper Casing ........................................................................................... 101 4.10.4 Die-Cavity .............................................................................................................. 102
CHAPTER 5 – DRAFTING................................................................................104
5.1 OVERVIEW .....................................................................................................................104 5.2 CREATING A DRAFTING .............................................................................................105 5.3 DIMENSIONING .............................................................................................................110 5.4 SECTIONAL VIEW .........................................................................................................112 5.5 PRODUCT AND MANUFACTURING INFORMATION .............................................114 5.6 EXAMPLE ........................................................................................................................117 5.7 EXERCISE........................................................................................................................121
CHAPTER 6 – ASSEMBLY MODELING .......................................................122
6.1 TERMINOLOGY .............................................................................................................122 6.2 ASSEMBLING APPROACHES ......................................................................................123
6.2.1 Top-Down Approach................................................................................................ 123 6.2.2 Bottom-Up Approach ............................................................................................... 123 6.2.3 Mixing and Matching ............................................................................................... 124 6.3 ASSEMBLY AND CONSTRAINT NAVIGATORS ......................................................124 6.4 MATING CONSTRAINTS ..............................................................................................124 6.5 EXAMPLE ........................................................................................................................125 6.5.1 Starting an Assembly ............................................................................................... 126 6.5.2 Adding Components and Constraints....................................................................... 128 6.5.3 Exploded View ......................................................................................................... 138 6.6 EXERCISES .....................................................................................................................142 6.6.1 Arbor Press ............................................................................................................... 142 6.6.2 Butterfly Valve ......................................................................................................... 142 6.6.3 Jackscrew ................................................................................................................. 146
CHAPTER 7 – FREEFORM SURFACE MODELING ..................................148
7.1 OVERVIEW .....................................................................................................................148
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7.1.1 Creating Freeform Features from Points .................................................................. 148 7.1.2 Creating Freeform Features from Section Strings.................................................... 149 7.1.3 Creating Freeform Features from Faces ............................................................... 150 7.2 FREEFORM FEATURE MODELING ............................................................................150 7.2.1 Modeling with Points ............................................................................................... 151 7.2.2 Modeling with a Point Cloud ................................................................................... 152 7.2.3 Modeling with Curves .............................................................................................. 154 7.2.4 Modeling with Curves and Faces ............................................................................. 156 7.3 EXERCISES .....................................................................................................................158 7.3.1 An Exercise on Curves ............................................................................................. 158 7.3.2 An Exercise on Surfaces........................................................................................... 159 7.3.3 Design a Computer Mouse ....................................................................................... 160 7.3.4 Design a Sport Water Bottle..................................................................................... 160
CHAPTER 8 – FINITE ELEMENT ANALYSIS.............................................161
8.1 OVERVIEW .....................................................................................................................161 8.1.1 Element Shapes and Nodes ...................................................................................... 161 8.1.2 Solution Steps........................................................................................................... 163 8.1.3 Simulation Navigator ............................................................................................... 164
8.2 SIMULATION CREATION.............................................................................................164 8.3 MATERIAL PROPERTIES .............................................................................................167 8.4 MESHING ........................................................................................................................169 8.5 LOADS .............................................................................................................................170 8.6 BOUNDARY CONDITIONS...........................................................................................171 8.7 RESULT AND SIMULATION ........................................................................................172
8.7.1 Solving the Simulation ............................................................................................. 172 8.7.2 FEA Result ............................................................................................................... 174 8.7.3 Simulation and Animation ....................................................................................... 177 8.8 EXERCISES .....................................................................................................................180 8.8.1 Arbor Press Bar ........................................................................................................ 180 8.8.2 Rocker Arm .............................................................................................................. 181
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CHAPTER 9 – MANUFACTURING ................................................................182
9.1 GETTING STARTED ......................................................................................................182 9.1.1 Creation of a Blank .................................................................................................. 182 9.1.2 Setting Machining Environment .............................................................................. 184 9.1.3 Operation Navigator ................................................................................................. 185 9.1.4 Machine Coordinate System (MCS) ........................................................................ 185 9.1.5 Geometry Definition ................................................................................................ 186
9.2 CREATING OPERATION ...............................................................................................187 9.2.1 Creating a New Operation ........................................................................................ 187 9.2.2 Tool Creation and Selection ..................................................................................... 188 9.2.3 Tool Path Settings .................................................................................................... 191 9.2.4 Step Over and Scallop Height .................................................................................. 192 9.2.5 Depth Per Cut ........................................................................................................... 193 9.2.6 Cutting Parameters ................................................................................................... 193 9.2.7 Avoidance................................................................................................................. 194 9.2.8 Speeds and Feeds ..................................................................................................... 195
9.3 PROGRAM GENERATION AND VERIFICATION .....................................................197 9.3.1 Generating Program ................................................................................................. 197 9.3.2 Tool Path Display..................................................................................................... 197 9.3.3 Tool Path Simulation................................................................................................ 198 9.3.4 Gouge Check ............................................................................................................ 200
9.4 OPERATION METHODS................................................................................................201 9.4.1 Roughing .................................................................................................................. 201 9.4.2 Semi-Finishing ......................................................................................................... 201 9.4.3 Finishing Profile ....................................................................................................... 204 9.4.4 Finishing Contour Surface ....................................................................................... 208 9.4.5 Flooring .................................................................................................................... 212
9.5 POST PROCESSING .......................................................................................................215 9.5.1 Creating CLSF.......................................................................................................... 216 9.5.2 Post Processing......................................................................................................... 217
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PREFACE
NX is one of the world’s most advanced and tightly integrated CAD/CAM/CAE product development solution from Siemens PLM Software. Spanning the entire range of product development, NX delivers immense value to enterprises of all sizes. It simplifies complex product development, thus speeding up the process of introducing products to the market.
The NX software integrates multidisciplinary principles, conceptual design, 3D modeling, documentation, engineering analysis, graphic simulation, and concurrent engineering. The software has powerful hybrid modeling capabilities by integrating constraint-based feature modeling and explicit geometric modeling. In addition to modeling standard geometry parts, it allows the user to design complex freeform shapes such as airfoils and manifolds. It also merges solid and surface modeling techniques into one powerful toolset.
This self-guided tutorial provides a step-by-step approach for users to learn NX 12. It is intended for those with no previous experience with NX. However, users of previous versions of NX may also find this tutorial useful for them to learn the new user interfaces and functions. The user will be guided from starting an NX 12 session to creating models and designs that have various applications. Each chapter has components explained with the help of various dialog boxes and screenshots. These components are later used in the assembly modeling, machining and finite element analysis. The files of components are also available online to download and use. We first released the tutorial for Unigraphics 18 and later updated for NX 2 followed by the updates for NX 3, NX 5, NX 7, NX 9 and NX 10. This write-up further updates to NX 12.
Our previous efforts to prepare the NX self-guided tutorial were funded by the National Science Foundation’s Advanced Technological Education Program and by the Partners of the Advancement of Collaborative Engineering Education (PACE) program.
If you have any questions or comments about this tutorial, please email Ming C. Leu at [email protected] or Wenjin Tao at [email protected] The models and all the versions of the tutorial are available at http://web.mst.edu/~mleu.

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CHAPTER 1 – INTRODUCTION
The modern manufacturing environment can be characterized by the paradigm of delivering products of increasing variety, smaller batches and higher quality in the context of increasing global competition. Industries cannot survive worldwide competition unless they introduce new products with better quality, at lower costs and with shorter lead-time. There is intense international competition and decreased availability of skilled labor. With dramatic changes in computing power and wider availability of software tools for design and production, engineers are now using Computer Aided Design (CAD), Computer Aided Manufacturing (CAM) and Computer Aided Engineering (CAE) systems to automate their design and production processes. These technologies are now used every day for all sorts of different engineering tasks. Below is a brief description of how CAD, CAM, and CAE technologies are being used during the product realization process.
1.1 PRODUCT REALIZATION PROCESS
The product realization process can be roughly divided into two phases: design and manufacturing. The design process starts with identification of new customer needs and design variables to be improved, which are identified by the marketing personnel after getting feedback from the customers. Once the relevant design information is gathered, design specifications are formulated. A feasibility study is conducted with relevant design information and detailed design and analyses are performed. The detailed design includes design conceptualization, prospective product drawings, sketches and geometric modeling. Analysis includes stress analysis, interference checking, kinematics analysis, mass property calculations and tolerance analysis, and design optimization. The quality of the results obtained from these activities is directly related to the quality of the analysis and the tools used for conducting the analysis.
The manufacturing process starts with the shop-floor activities beginning from production planning, which uses the design process drawings and ends with the actual product. Process planning includes activities like production planning, material procurement, and machine selection. There are varied tasks like procurement of new tools, NC programming and quality checks at various stages during the production process. Process planning includes planning for all

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the processes used in manufacturing of the product. Parts that pass the quality control inspections are assembled functionally tested, packaged, labeled, and shipped to customers.
A diagram representing the Product Realization Process (Mastering CAD/CAM, by Ibrahim Zeid, McGraw Hill, 2005) is shown below.

1.2 BRIEF HISTORY OF CAD/CAM DEVELOPMENT
The roots of current CAD/CAM technologies go back to the beginning of civilization when engineers in ancient Egypt recognized graphics communication. Orthographic projection practiced today was invented around the 1800s. The real development of CAD/CAM systems started in the 1950s. CAD/CAM went through four major phases of development in the last century. The 1950s was known as the era of interactive computer graphics. MIT’s Servo Mechanisms Laboratory demonstrated the concept of numerical control (NC) on a three-axis milling machine. Development in this era was slowed down by the shortcomings of computers at the time. During the late 1950s

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