cad final project ppt

8/8/2019 CAD Final Project Ppt

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By:

Sidhant Sharma Date: 12/15/2010


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Introduction

Automation

Basic termin0logies


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AutomationAutomation is the use of control systems and information

technologies to reduce the need for human work in industry

Mechanization on the other hand is the aid of machinery toassist humans with the muscular requirements of work

Need for Automationy Higher production rates

y

Increase in accu

racyy Replacing human operators in hard physical, monotonous or dangerous

work

y Performing tasks beyond human capabilities of size, weight, speed,endurance, etc.

y Economy improvement


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Basic terminologies Welding A fabrication process that joins materials,

usually metals or thermoplastics, by causing

coalescence. Eg. gas welding, resistance welding,

friction welding, laserbeam welding, etc.

FixtureA device which locates and secures a

workpiece during a machining operation

Features of a fixture -

y Location systemy Clamping system

y Control system

y Foolproofing and asymmetry

y Weight and Handling


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Product and systemdescription


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Product and System descriptionA Safe (also called strongbox) is a secure lockable box used for

securing valuable objects against theft or damage

Two models of DefenderPlus Safes from Godrej & Boyce Mfg.

Co. Ltd. are shown below

61 (height) model

26 model


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Product and System description contd.. The 61 model is composed of three subassemblies

1. Inner body

2. Door

3. Outer body - Fixture is being designed for making this

subassembly (shown in next slide)

1. Inner body being inserted 2. Door assembly


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Problem description


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Problem description : To design a pneumatic

welding fixture for outer body subassembly

3. Outer body subassembly and operations

Leftshell

Rightshell

Lug


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Why is the problem worth study??

y Design : Designing a fixture involves designing all of itselements i.e location, clamping, control systems

y Motion Study: Motion study is a necessity as the fixtureinvolves moving elements that must move precisely so as

to maintain tolerances

y Optimization: The problem breaks down into a multi-optimization problem as we optimize the assemblysequence, process sequence, setup-time, etc.

y FEA : We analyze the clamping forces and their effects on

the parts as a preventive measure


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Design goalsy To design the location system

y To design pneumatic clamps for the clamping system

y To carry out mechanical simulation on the fixture, which

will help in fixing the location, design and geometry ofclamps

y To optimize the setup time on the fixture

y To optimize the sequence of assembly of the outer body

y To design the control electro-pneumatic circuit for the

finalized motion sequence


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Survey of pneumatic

clamping mechanisms


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Pneumatic Clamping Mechanisms


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Alternative fixture designs


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Design 1

Design 2


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Decision making : Final Design

Weightage to factors out of 1

Sr no Factors Design 1 Design 2 Selection

1 Pneumatic elements no. 0 1Design 2

2 Weight of fixture 0 1 Design 2

3 Workpiece securing 1 0Design 1

4

Ease of welding

operation 0 1

Design 2

5 Setup time 0 1Design 2

6

Spacing for pneumatic

wiring 0 1Design 2

7 Sequence control0 1 Design 2

8 Design of circuit 1 1 Design 1,2


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CADModels


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Horizontal toggle clamp

cad final project simulationvideos\horizontal pneumatictoggle clamp mechanism.avi


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Hold down clamp

cad final project simulationvideos\vertical pneumatic

toggle clamp mechanismsimulation.avi


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Final fixture assembly


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Geometric Analysis

Lug location system

Right shell location


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Motion analysis

It can be observed that 24 mm of the piston stroke is converted into 11 mm ofthe clamping rod movement through the toggle mechanism. Thus we can fix

the clamping bar 8-10 mm away from the su

rface to be clamped.

Piston rod displacement Clamping rod displacement


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Motion analysis contd..

For 24 mm of the piston stroke the clamping point moves 55mm horizontally and 88 mm vertically. Thus we placed it 40mm horizontally and 20 mm below the point to be clamped.

iston rod displacement lamping rod path trace


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Setup time analysis resultsSet

ti e(sec)

r cess

ti e(sec)

Trial sequence 64 5

Trial sequence 47 98

Difference 17 17

cad final project simulationvideos\fixture trial2.avi

fixture mechsimulation setup timeanalysis.xlsx


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Clamping force and stress analysis

Horizontal clamp force

Lug clamp force Lug

Left shell


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Clamping force and stress analysis contd..

Old design of

lug clampingrod

New design withreduced stress

by approx. 50 %


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Electro pneumatic system equivalent

Fixture mechanical system


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Electro pneumatic control circuit

cad final project simulationvideos\IMG_0132.MOV


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ChallengesThe main problems faced in the project were-

y Setting up the event based motion sequence inSolidworks as there was no provision for event based

motion simu

lation in the premiu

m versiony High computation times as the simulation was upto 1

minute in certain cases

Solution: The event based problem was solved by theuse of independent linear motors to control the motionof each pneumatic clamp independently in the requiredsequence


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Website demo

https://sites.google.com/site/sidhantsharmacadapplications/


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ReferencesBOOKS

[1] Jigs and Fixture Design by Edward Hoffman

[2] Design of Jigs and Fixtures by Joshi

WEBSITES

[1] www.wikipedia.com[2] www.youtube.com

[3] http://www.drillspot.comp


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Questions??

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