# Apostila NX 5

(Parte 1 de 8)

UNIGRAPHICS-NX3 FOR

By Parthiban Delli

Ming Leu

Department of Mechanical and Aerospace Engineering

University of Missouri – Rolla Rolla, Missouri 65401

This project is funded by the National Science Foundation

Advanced Technological Education Program and Partners of the Advancement of Collaborative Engineering Education

 FOREWORD 6 CHAPTER 1 - INTRODUCTION 7 1.1 PRODUCT REALIZATION PROCESS 7 1.2 BRIEF HISTORY OF CAD/CAM DEVELOPMENT 8 1.3 DEFINITION OF CAD/CAM/CAE 10 1.3.1 Computer Aided Design – CAD 10 1.3.2 Computer Aided Manufacturing – CAM 10 1.3.3 Computer Aided Engineering – CAE 10 1.4 SCOPE OF THIS TUTORIAL 1 CHAPTER 2 - GETTING STARTED IN UNIGRAPHICS 13 2.1 OPENING UNIGRAPHICS AND FILES 13 2.1.1 Open Unigraphics 13 2.1.2 Open a New File 14 2.1.3 Open a Part File 15 2.2 PRINTING, SAVING AND CLOSING PART FILES 16 2.2.1 Print a Unigraphics Image 16 2.2.2 Save Part Files 17 2.2.3 Close Part Files 17 2.2.4 Exit an Unigraphics Session 18 2.2.5 Simultaneously Saving All Parts and Exiting 18 2.3 UNIGRAPHICS-NX3 INTERFACE: 18 2.3.1 Mouse Functionality 19 2.3.2 Unigraphics Gateway 21 2.3.3 Geometry Selection 24 2.3.4 User Preferences 27 2.4 COORDINATE SYSTEMS 30 2.4.1 Absolute Coordinate System 30 2.4.2 Work Coordinate System 30 2.4.3 Existing Coordinate Systems 30 2.4.4 Move the WCS 30 2.5 USING LAYERS 31 2.5.1 Layer Control 31 2.5.2 Commands in Layers 32 2.6 IMPORTANT COMMANDS/DIALOGS 36 2.6.1 Toolbars 36 2.6.2 Transform Functions 37 CHAPTER 3 - FORM FEATURES 39 3.1 OVERVIEW 39 3.2 TYPES OF FEATURES 39 3.3 PRIMITIVES 43

INDEX 3.3.1 Model a Block ....................................................................................................... 43

 3.4 REFERENCE FEATURES 48 3.4.1 Datum Plane 48 3.4.2 Datum Axis 50 3.5 SWEPT FEATURES 51 3.5.1 Extruded Body 51 3.6 REMOVE FEATURES 54 3.7 EXERCISE - MODEL A WASHER 57 CHAPTER 4 – FEATURE OPERATIONS 58 4.1 OVERVIEW 58 4.2 TYPES OF FEATURE OPERATIONS 58 4.3 FEATURE OPERATIONS ON MODELS 63 4.3.1 Model a Hexagonal Screw 63 4.3.2 Model an L-Bar 68 4.3.3 Model a Hexagonal Nut 75 4.3.4 Model a Rack with Instances 78 4.4 EXERCISE - MODEL A CIRCULAR BASE 83 CHAPTER 5 – DRAFTING 84 5.1 OVERVIEW 84 5.2 DRAFTING OF MODELS 85 5.2.1 Drafting 85 5.2.2 Dimensioning 90 5.2.3 Sectional View 95 5.2.4 Drafting and Dimensioning of an Impeller hexagonal bolt 96 5.3 EXERCISE - DRAFTING AND DIMENSIONING OF A CIRCULAR BASE 100 CHAPTER 6 – SKETCHING 101 6.1 OVERVIEW 101 6.2 SKETCHING FOR CREATING MODELS 102 6.2.1 Model an Arbor press Base 103 6.2.2 Model an Impeller Lower Casing 115 6.2.3 Model an Impeller 123 6.3 EXERCISES 127 CHAPTER 7 – FREEFORM FEATURE 130 7.1 OVERVIEW 130 7.1.1 Creating Freeform Features from Points 130 7.1.2 Creating Freeform Features from Section Strings 131 7.1.3 Creating Freeform Features from Faces 133 7.2 FREEFORM FEATURE MODELING 133 7.2.1 Modeling with points 133 7.2.2 Modeling with a point cloud 137 7.2.3 Modeling with curves 139 7.2.4 Modeling with curves and faces 142 Unigraphics-NX3 for Engineering Design University of Missouri - Rolla 3

3.3.2 Model a Shaft ........................................................................................................ 45 7.3 EXERCISE - MODEL A MOUSE.............................................................................145

 8.1 OVERVIEW 146 8.2 TERMINOLOGIES 146 8.3 ASSEMBLY MODELS 147 8.3.1 Top-Down Modeling 147 8.3.2 Bottom-Up Modeling 148 8.3.3 Mixing and Matching 148 8.4 MATING CONDITIONS 148 8.5 IMPELLER ASSEMBLY 150 8.6 EXPLODED VIEW OF IMPELLER ASSEMBLY 164 8.7 EXERCISE - ARBOR PRESS ASSEMBLY 169 CHAPTER 9- MANUFACTURING 170 9.1 GETTING STARTED WITH MANUFACTURING MODULE 170 9.1.1 Creation of Blank 170 9.1.2 Setting Machining Environment 172 9.1.3 Operation Navigator 173 9.1.4 Machine Coordinate System (MCS) 174 9.1.5 Geometry Definition 174 9.2 CREATING OPERATION AND PARAMETER SETTING 176 9.2.1 Creating a new Operation 176 9.2.3 Tool Creation and Selection 177 9.2.4 Cut Method 180 9.2.4 Step Over and Scallop Height: 181 9.2.5 Depth per cut 182 9.2.6 Cutting Parameters 183 9.2.7 Avoidance 185 9.2.8 Feedrates 186 9.3 PROGRAM GENERATION AND VERIFICATION 188 9.3.1 Generating Program 188 9.3.2 Tool Path Display 189 9.3.3 Tool Path Simulation 189 9.3.4 Gouge Check 193 9.4 OPERATION METHODS 193 9.4.1 Roughing 193 9.4.2 Semi-Finishing 194 9.4.3 Finishing Profile 197 9.4.4 Finishing Contour Surface 205 9.4.5 Flooring 210 9.5 POST PROCESSING 213 9.5.1 Creating CLSF 214 9.5.2 Postprocessing 216 CHAPTER 10- FINITE ELEMENT ANALYSIS 218 10.1 INTRODUCTION TO FEA 218 Unigraphics-NX3 for Engineering Design University of Missouri - Rolla 4
 10.1.3 Scenario Navigator 2 10.1 SCENARIO CREATION 2 10.2.1 Material Properties 224 10.2.2 Loads 224 10.2.3 Boundary Conditions 225 10.2.4 Meshing 226 10.3 SOLVING AND RESULT SIMULATION 228 10.3.1 Solving the Scenario 228 10.3.2 FEA Result 229 10.3.2 Simulation 231 Unigraphics-NX3 for Engineering Design University of Missouri - Rolla 5

10.1.2 Structure Module ............................................................................................... 220 10.4 EXERCISE-ARBORPRESS L-BAR........................................................................ 234

Unigraphics is one of the world’s most advanced and tightly integrated CAD/CAM/CAE product development solutions. Spanning the entire range of product development, Unigraphics delivers immense value to enterprises of all sizes. It simplifies complex product designs, thus speeding up the process of introducing products to the market.

The Unigraphics software integrates knowledge-based principles, industrial design, geometric modeling, advanced 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 free-form shapes such as airfoils and manifolds. It also merges solid and surface modeling techniques into one powerful tool set.

This self-guiding tutorial provides a step-by-step approach for users to learn Unigraphics. It is intended for those with no previous experience with Unigraphics. However, users of previous versions of Unigraphics may also find this tutorial useful for them to learn the new user interfaces and functions. The user will be guided from first starting a Unigraphics session to creating models and designs that have various applications. Each chapter has components explained with the help of various dialog boxes and screen images. These components are later used in the assembly modeling, machining and finite element analysis. These models of components are available online to download and use. We first released the Tutorial for Version 18 and later updated for NX-2. This write-up is further updated to Unigraphics NX-3.

 http://web.umr.edu/~mleu/

If you have any questions or comments about this tutorial, please email Parthiban Delli at pdwt5@umr.edu. The Models and all the versions of the Tutorial are available at Unigraphics-NX3 for Engineering Design University of Missouri - Rolla 6

CHAPTER 1 - INTRODUCTION

The modern manufacturing environment can be characterized by the paradigm of delivering products of increasing variety, smaller lots 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 intensified 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 everyday for engineering tasks. Below is a brief description of how CAD, CAM, and CAE technologies are used during the product realization process.

1.1 PRODUCT REALIZATION PROCESS

The product realization process can be divided into design and manufacturing. The design process starts with identification of a new design need that is identified after the marketing personnel gets feedback from customers’ demands. Once the relevant design information is gathered, design specifications are formulated. Next, a feasibility study is done with relevant design information. Detailed design and analyses then follow. 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.

The manufacturing process starts with the shop-floor activities beginning from production planning, which uses the drawings from the design process and ends with the actual product. Process planning includes activities like production plan, material orders, and machine selection. There are varied tasks like procurement of new tools, NC programming and quality checks at various stages during production. Process planning includes planning for all these activities as well. Parts that pass the quality control inspections are assembled functionally tested, packaged, labeled, and shipped to customers.

Unigraphics-NX3 for Engineering Design University of Missouri - Rolla 7

A diagram representing the Product Realization Process [1] is shown below. ([1] – CAD/CAM, by Ibrahim Zeid)

1.2 BRIEF HISTORY OF CAD/CAM DEVELOPMENT

The roots of today’s CAD/CAM technologies go back to the beginning of civilization when graphics communication was recognized by engineers in ancient Egypt. 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 the development of Automatically Programmed Tools (APT) began and General Motors explored the potential of interactive graphics.

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The 1960s was the most critical research period for interactive computer graphics. Ivan Sutherland developed a sketchpad system, which demonstrated the possibility of creating drawings and altercations of objects interactively on a cathode ray tube (CRT). The term CAD started to appear with the word ‘design’ extending beyond basic drafting concepts. General Motors announced their DAC-1 system and Bell Technologies introduced the GRAPHIC 1 remote display system.

During the 1970s, the research efforts of the past decade in computer graphics had begun to be fruitful, and important potential of interactive computer graphics in improving productivity was realized by industry, government and academia. The 1970s is characterized as the golden era for computer drafting and the beginning of ad hoc instrumental design applications. National Computer Graphics Association (NCGA) was formed and Initial Graphics Exchange Specification (IGES) was initiated.

In the 1980s new theories and algorithms evolved and integration of various elements of design and manufacturing was developed. The major research and development focus was to expand CAD/CAM systems beyond three-dimensional geometric designs and provide more engineering applications.

In the present day, CAD/CAM development is focused on efficient and fast integration and automation of various elements of design and manufacturing along with the development of new algorithms. There are many commercial CAD/CAM packages available for direct usages that are user-friendly and very proficient.

Here are some of the commercial packages in the present market.

• AutoCAD and Mechanical Desktop are some low end CAD softwares which are mainly used for 2D modeling and drawing.

• Unigraphics, Pro-E, Mechanical Desktop, CATIA and Euclid are higher order modeling and designing software that are costlier but more efficient. The other capabilities of these softwares are manufacturing and analysis.

• Ansys, Abaqus, Nastran, Fluent and CFX are packages mainly used for analysis of structures and fluids. Different software are used for different proposes. For example, Fluent is used for fluids and Ansys is used for structures.

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• Alibre, Cyber-Cut and CollabCAD are the latest CAD/CAM softwares which focus on collaborative design. Collaborative design is computer aided designing for multiple users working at the same time.

1.3 DEFINITION OF CAD/CAM/CAE

1.3.1 Computer Aided Design – CAD

CAD is technology concerned with using computer systems to assist in the creation, modification, analysis, and optimization of a design. Any computer program that embodies computer graphics and an application program facilitating engineering functions in design process can be classified as CAD software.

The most basic role of CAD is to define the geometry of design – a mechanical part, a product assembly, an architectural structure, an electronic circuit, a building layout, etc. The greatest benefits of CAD systems are that they can save considerable time and reduce errors caused by otherwise having to redefine the geometry of the design from scratch every time it is needed.

1.3.2 Computer Aided Manufacturing – CAM

 operations through computer interface with the plant’s production resources

CAM technology involves computer systems that plan, manage, and control the manufacturing

One of the most important areas of CAM is numerical control (NC). This is the technique of using programmed instructions to control a machine tool that cuts, mills, grinds, punches or turns raw stock into a finished part. Another significant CAM function is in the programming of robots. Process planning is also a target of computer automation.

1.3.3 Computer Aided Engineering – CAE

CAE technology uses a computer system to analyze the functions of a CAD-created product, allowing designers to simulate and study how the product will behave so that the design can be refined and optimized.

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CAE tools are available for a number of different types of analyses. For example, kinematic analysis programs can be used to determine motion paths and linkage velocities in mechanisms. Dynamic analysis programs can be used to determine loads and displacements in complex assemblies such as automobiles. One of the most popular methods of analyses is using a Finite Element Method (FEM). This approach can be used to determine stress, deformation, heat transfer, magnetic field distribution, fluid flow, and other continuous field problems that are often too tough to solve with any other approach.

1.4 SCOPE OF THIS TUTORIAL

This tutorial is written for students and engineers who are interested in learning how to use Unigraphics for designing mechanical components and assemblies. Learning to use this software will also be valuable for learning how to use other CAD systems such as PRO-E and CATIA.

This tutorial provides a step-by-step approach for learning Unigraphics. The topics include Getting Started with Unigraphics, Form Features, Feature Operations, Drafting, Sketching, Free Form Features, Assembly Modeling, and Manufacturing.

Chapter 1 gives the overview of CAD/CAM/CAE. Here, the product realization cycle is discussed along with the history of CAD/CAM/CAE and the definitions of each.

 other important commands, which will be used in later chapters

Chapter 2 includes the Unigraphics essentials from starting a session with Windows to getting familiar with the Unigraphics-NX3 layout by practicing basic functions such as Print, Save, and Exit. It also gives a brief description of the Coordinate System, Layers, various tool boxes and

The actual designing and modeling of parts begins with chapter 3. It describes different features such as reference features, swept features and primitive features and how these features are used to create designs.

Chapter 4 is a continuation of chapter 3 where various kinds of operations are performed on features. The different kinds of operations include Trim, Blend, Boolean operations and many more.

You will learn how to create a drawing from a part model in chapter 5. In this chapter, we demonstrate how to create a drawing by adding views, dimensioning the part drawings, and modifying various attributes in the drawing such as text size, arrow size and tolerance.

(Parte 1 de 8)