CAD Final Project Ppt - Copy

By: Sidhant Sharma

Date: 12/15/2010

Agenda Introduction Automation Basic Terminologies Product and System Description Problem Description Reasons for choosing the problem Design goals Survey Alternative designs Analysis Problems faced Webpage

Introduction Automation Basic termin0logies

Automation Automation 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 to assist humans with the muscular requirements of work Need for Automationy Higher production rates y Increase in accuracy y 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

Common types of Automation Electrical Hydraulic Pneumatic

fast, reliable, precise but expensive high forces possible but prone to leakage cheap, small but slow in operation and provides low force

Combined systems y Electro-hydraulic y Hydro-pneumatic y Electro-pneumatic

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. Fixture A device which locates and secures a workpiece during a machining operation y y y y y

Features of a fixture Location system Clamping system Control system Foolproofing and asymmetry Weight and Handling

Product and system description

Product and System description A Safe (also called strongbox) is a secure lockable box used for securing valuable objects against theft or damage Two models of Defender Plus Safes from Godrej & Boyce Mfg. Co. Ltd. are shown below61 (height) model

26 model

Product and System description contd.. The 61 model is composed of three subassemblies1. 2. 3.

Inner body Door Outer body - Fixture is being designed for making this subassembly (shown in next slide)

1. Inner body being inserted

2. Door assembly

Problem description

Problem description : To design a pneumatic welding fixture for outer body subassembly

Left shell Right shell

Lug

3. Outer body subassembly and operations

Why is the problem worth study??y Design : Designing a fixture involves designing all of its

elements i.e location, clamping, control systemsy Motion Study: Motion study is a necessity as the fixture

involves moving elements that must move precisely so as to maintain tolerancesy Optimization: The problem breaks down into a multi-

optimization problem as we optimize the assembly sequence, process sequence, setup-time, etc.y FEA : We analyze the clamping forces and their effects on

the parts as a preventive measure

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 of clamps 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

Survey of pneumatic clamping mechanisms

Pneumatic Clamping Mechanisms

Alternative fixture designs

Design 1

Design 2

Decision making : Final DesignWeightage to factors out of 1Sr no Factors Design 1 Design 2 Selection Design 2 Design 2 Design 1 Design 2 Design 2 Design 2 Design 2 Design 1,2

1 2 3 4 5 6 7 8

Pneumatic elements no. Weight of fixture Workpiece securing Ease of welding operation Setup time Spacing for pneumatic wiring Sequence control Design of circuit

0 0 1 0 0 0 0 1

1 1 0 1 1 1 1 1

CAD Models

Horizontal toggle clampcad final project simulation videos\horizontal pneumatic toggle clamp mechanism.avi

Hold down clampcad final project simulation videos\vertical pneumatic toggle clamp mechanism simulation.avi

Final fixture assembly

Analysis and Results

Geometric AnalysisLug location system

Right shell location

Motion analysis

Piston rod displacement

Clamping rod displacement

It can be observed that 24 mm of the piston stroke is converted into 11 mm of the clamping rod movement through the toggle mechanism. Thus we can fix the clamping bar 8-10 mm away from the surface to be clamped.

Motion analysis contd..

iston rod displacement

lamping rod path trace

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

Setup time analysis resultsSet ti e(sec) Trial sequence Trial sequence Difference 64 47 17 r cess ti e(sec) 5 98 17

cad final project simulation videos\fixture trial2.avi fixture mech simulation setup time analysis.xlsx

Clamping force and stress analysis

Horizontal clamp force

Left shell

Lug clamp force

Lug

Clamping force and stress analysis contd..

Old design of lug clamping rod

New design with reduced stress by approx. 50 %

Electro pneumatic system equivalent

Fixture mechanical system

Electro pneumatic control circuit

cad final project simulation videos\IMG_0132.MOV

Design-Analysis Optimization flow sequenceDesign of fixture elements Optimum placement using motion simulation Designing the Assembly sequence Designing the Motion sequence Setup time analysis Optimization of motion and assembly sequence Clamping force and stress analysis Design changes in clamping elements to reduce stress Final design of system Design of electro pneumatic control circuit

ChallengesThe main problems faced in the project werey Setting up the event based motion sequence in Solidworks as there was no provision for event based motion simulation in the premium version y High computation times as the simulation was upto 1 minute in certain cases Solution: The event based problem was solved by the use of independent linear motors to control the motion of each pneumatic clamp independently in the required sequence

Website demo

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

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

Questions??