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Transcript of Lecture Week1
MT 21_CAD/CAM 3(1-2)
Lecture: Week 1
Than Lin, Ph.D.Instructor, Undergraduate Program
Asian Institute of Technology
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Grading: Quizzes (10%) Mid Term Exam (30%)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Grading: Quizzes (10%) Mid-Term Exam (30%) Laboratory Exercises (10%) & Project (10%) and Final Exam (40%)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Textbook:
Kunwoo Lee “Principles of CAD/CAM/CAE Systems.
ReferencesReferences:
Farid M. Amirouche, Principles of Computer Aided Design and Manufacturing, 2nd Edition Prentice Hall 20042nd Edition, Prentice-Hall, 2004.
P N Rao “CAD/CAM Principles and Applications”
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Introduction to CAD/CAM/CAE
ContentsOverviewD fi iti f CAD CAM d CAE
Contents
Definitions of CAD, CAM, and CAE Integrating the Design and Manufacturing Processh h C D bthrough a Common Database
Using CAD/CAE/CAM Systems for d l i l lProduct Development- Practical Example
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Overview
CAD/CAM 3(1-2), AIT-UG (January’ 2013)Figure: Product Cycle
Result of Synthesis
• A conceptual design of the prospective product in the form of sketch (layout drawing)that shows the relationships among the various product components
• The major financial commitments needed to realize the product idea are made• The functionality of the product is determined• Most of the information generated and handled is qualitative and consequently is hard
to capture in the computer system
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Analysis Sub-Processes
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Definitions of CAD/CAM/CAE
Computer Aided Design (CAD) –The technology concerned with the use of t t t i t i th ti difi ti l i dcomputer systems to assist in the creation, modification, analysis, and
optimization of a design [Groover and Zimmers 1984]
Computer Aided Manufacturing (CAM)- the technology concerned with the use of computer systems to plan, manage, and control manufacturing operations through either direct or indirect computer interface with the plant’s production resources
Computer Aided Engineering (CAE)- The technology concerned with the use of computer systems to analyze CAD geometry, allowing the designer to simulate and study how the product will behave so that the design can be refined and optimized
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Definitions of CAD/CAM/CAE
CAD,CAM, and CAE- Concerned with automating specific functions of the product cycle and making more efficient
Developments done separately not fully realized the potential of integratingDevelopments done separately, not fully realized the potential of integrating the design and manufacturing activities of the product cycle
CIM has been introduced to solve this problem, aimed at trying the separate “islands of automation” together into a smoothly running, efficient system.
CIM-concerned with using the computer database as a way to run an entire enterprise more efficiently, having an impact on accounting, scheduling,enterprise more efficiently, having an impact on accounting, scheduling, shipping, and other management functions
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Integrating the Design & Manufacturing Process through a common database-A Scenario
To show how CAD/CAM/CAE are overlaid on the product cycle to
common database A Scenario
id on the product cycle to realize the goals of better quality(Q), lower Cost©, and Quick delivery(D)
Assume [Design specification calls for the cabinet to have four spaces]
Fi A di tp ]
-Disc player-Cassette playerReceiver
Figure: Audio system cabinet to be
designed-Receiver-Storage compartment
Designer to determine Dimensions of Cabinet, Material, thickness and considers assembly
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
y
Integration of CAD/CAM/CAE through the data-base
Figure: Integration of CAD,CAM and CAE through the database
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
the database
Using CAD/CAM/CAE Systems for Product Development-A Practical Example
-Task To design & Manufacture
the front piece of cellular phonethe front piece of cellular phone
-Assume that Styling and
conceptual design carried outp g
CAD
CAM
Mold Design
Mold FlowCAM
Mold Assembly
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
A case study of CAD/CAE/CAM
Four steps in the product cycle of this arm lift weightFour steps in the product cycle of this arm lift weight
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Step 1Conceptual and geometric design (CAD)
Design - Using drafting software to draw the outline curve
M d l U i 3D d li ft t d l th tModel - Using 3D modeling software to model the part as a revolution surface
Database - Store the design as a file in computer
Computer-aided drafting system and geometric modeling system are the two most important components of CAD.system are the two most important components of CAD.
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Step 2Analysis of CAD geometry and optimization (CAE)
SimulationSimulation
Analyses of stress, strain, deformation, heat transfer, kinemay , , , ,tics, linkage, dynamics, fluid flow, etc.
Optimization
Fi it l t th d (FEM) i th t id l d th d iFinite-element method (FEM) is the most widely used method in CAE.
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Finite-Element Method
Finite-element modelingFinite element modeling Divide the CAD geometry into small pieces of required shaperequired shapeto approximate the design by a meshmesh.pp g y
Finite-element analysisFinite element analysisCalculate stress, strain, displacement etc. at any place in the model by solving a set of system equations and shape functioy g y q pns on the mesh.
(An Example)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Step 3Modify the design geometry (CAD again)
G t f d b k f th Fi it l t l iGet feed back from the Finite-element analysis
Modify the design geometry and other design data accModify the design geometry and other design data accordingly
(An Example)(An Example)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Step 4Make it, that is, manufacture it (CAM)
Manufacturing process planning Use computer technology to plan, manage, and control manufacturing process.
Numerical control (NC) machiningTh t h i f i d i t ti t t lThe technique of using programmed instructions to control a machine tool that grinds, cuts, mills, punches, bends, or turns raw stock into the finished partraw stock into the finished part.
Rapid prototypingRapid prototyping Build a prototype of the part directly from the CAD model as a stack of layers by means of laser or other techniques.
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
s c o ye s by e s o se o o e ec ques.
What is made of CAD/CAM/CAE
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Computer science: algorithms
Your program:
My program:
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Math: geometry
v2
p2v1
Gi t i t d d t t d
S(u) = ???p1y
Given two points p1 and p2, and two vectors v1 and v2,
find four vectors a0, a1, a2, and a3, such that the vector
function S(u) = a + a u + a u2 + a u3 satisfies:x function S(u) = a0 + a1u + a2u2 + a3u3 satisfies:
1. it is a smooth function in (0≤u≤1), and
2 its meets the boundary conditions2. its meets the boundary conditions
S(0) = p1 and dS(u)/du|u=0 = v1
S(1) = p2 and dS(u)/du|u 1 = v2
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
S(1) p2 and dS(u)/du|u=1 v2
Design the profile using a drafting software
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Modeling the part using a 3D geometric modeling software
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
ric modeling software
Basic 3D mesh elements
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
The triangular mesh of the model
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Property analysis
Finite element method (FEM) e e e e e od ( )or Finite difference method (FDM) or Finite volume method– For static and dynamics responses– Meshing boundary condition i
terationteration
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Property analysis
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Illustration of an FEM process
New design: one arc of radius 25 now should be a curve of height 25 and width 45 that is required to smoothly connect to its two adjoining lines.
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Before (without NC)
Now (with NC)
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
NC Machining ProgrammingTo program the NC machine tool to correctly cut the part
Given the CAD data:
1. How to compute the correct tool pathcorrect tool path (dotted)?
2. How to identify and determine the twodetermine the two phases of machining?
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Rapid Prototyping
Fi 1 A h ti d i f LOM
CAD/CAM 3(1-2), AIT-UG (January’ 2013)
Figure 1. A schematic drawing of a LOM process.Laminated Object Manufacturing