MUFFAKHAM JAH COLLEGE OF ENGINEERING AND

TECHNOLOGY

PROJECT SEMINARPROJECT GUIDE: D.SRINIVAS RAO (ASSOCIATE HEAD)

BY : MD NASEERUDDIN SHAH 1604-11-736-072 IBRAHIM MD AMEENUDDIN 1604-11-736-075 MOHD JALEELUDDIN 1604-11-736-105 MD SOHAIL KURANI 1604-11-736-135

DESIGN , ANALYSIS AND FABRICATION OF

QUICK RETURN MECHANISM

Introduction Basic Concepts Defining the Problem Overcoming the Problem Design Analysis Fabrication Application Conclusion Project Plan Methodology Bibliography

INDEX

Quick return mechanism, (QRM), is considered one of the important mechanisms

INTRODUCTION

Mechanism : It transforms or transfer motion

Link: Machine element which moves relative to other elements (machine)

a) Rigid link b) Flexible link

c) Fluid link

Basic Definitions

Kinematic pair : When two links are joint they constitute a pair

Joints : Junction of links

Type of motions possible between links• Revolute• Sliding

Four Bar Mechanism

Number of Links : 4

Number of Pairs : 4

Number of Fixed Links : 4

Slider Crank Mechanism

Modification of a basic four bar chain It consists of one sliding pair, three turning

pair

Method of obtaining different mechanisms by fixing different links in a kinematic chain

No. of Inversions possible = No. of links

No. of Inversions for four bar mechanism = 4

Inversions

Pendulum Pump Oscillating Cylinder Engine

Inversions of Slider Crank Chain

Rotary Internal Combustion Engine Crank and Slotted Lever Quick Return Mechanism

Whitworth Quick Return Mechanism

Lower Quick Return Ratio

Vibrations due to non linear velocity

Defining Problem

Rigid structure

Selection of material

Usage of Brass Bearings

Overcoming the problem

1.Forces acting on each link

2.Selecting materials

3.Suitable cross section

4.Link lengths

5.Machine power

Factors To Be Considered In Design

Design

Specifications and CalculationsStroke =120mm

Q.R =3

No.of strokes/min =50

Length AC = 40mm

Length BC = = = 56.57mm

Length AP = = =84.85mm

Length PR = 20mm

Dynamic Analysis

Calculation Of Forces

F6 = Τsteel *d* wF6 = 225*4*5F6 = 4500NF2 = F6

F5 =

F5 =

F5 =6364N

F4 = F5

Design of CrankMaximum force acting on Crank = 4500 * Impact Load Factor

= 4500*2 = 9000NCross-sectional Area Of Crank = Max Load / Permissible Stress

= 9000/200 = 45mm2 ………..1

Considering Rectangular Cross-Section, b=2d. C.S Area = b*d = 2d*d ………..2Equating 1 and 22d*d = 45d = 5mmb = 10mm

Design Of Slotted BarMaximum Force acting on Slotted Bar = 6364 * Impact Load Factor

= 6364*2 = 12728NCross-sectional Area Of Crank = Max Load / Permissible Stress

= 12728/200 = 64mm2 ………..1Considering Rectangular Cross-Section, b=2d. C.S Area = b*d = 2d*d ………..2Equating 1 and 22d*d = 64d = 6mmb = 12mm

Power Calculations

From Specifications

Mean Velocity = Stroke length * No. of strokes/mm= 120*100= 12 m/min

Power = Cutting Force * Mean Velocity= 4500*(12/60)= 900 watts (1.2 HP)

Including Friction and Inertia Forces 2HP Motor is required.

Design For Power Transmission RPM of the Crank = No. of Strokes per minute

To Convert 1400rpm motor motion into 100rpm motion V-Belt drive

For given loads Phosphor Bronze Bushings of required thickness should be used at Pin Joints between the links

Due to large fluctuations in loads Vibrations are induced.

To minimize these Vibrations, Cast Iron or Wooden Frame should be used

Positional Analysis

Velocity Analysis

Acceleration Analysis

Force Analysis

Analysis of Quick Return Mechanism

Data Acquisition System

System takes the analog output from the various sensors and converts them into digital values.

Digital analogous value is fed into the processing unit.

The computer uses software called KDM (Kinematics and Dynamics Of Machines).

The needed values and their characteristic curves are plotted by the software and the output is recorded.

Analysis SoftwaresMotion simulation softwaresCAE tools

Catia UG-NX NX I-DEAS SolidWorks

To study planar mechanism kinematics MatLab Simulink MapleSim SolidWorks

Software Analysis Procedure

Modeling the linkage using the motion simulation application (SolidWorks).

Import the model into Ansys

Analyse the meshed model in Ansys (Structural)

Study planar mechanism kinematics (position, velocity and acceleration) of the model using SolidWorks

Position analysis includes the position of links at different crank angle

From this we can determine the extreme positions of the mechanism

Position Analysis

Velocity Analysis deals with variation in velocity of slider at different instances

Velocity Analysis

Ground length = 25mm

When crank radius tends to ground length , QRR tends to infinite

Crank radius = 10mm

When ground length tends to crank radius length , QRR tends to infinite

QRR Vs Crank Radius , QRR Vs Ground length

FabricationFabrication is an industrial term refers to building metal structures by cutting, machining and drilling.The fabrication of quick return mechanism unit involves:

Cutting

Drilling

Machining

Welding

Grinding

Carpentry work

Fabrication of Crank and Connecting Rod

The cutting operation can be carried out in workshop

For better accuracy , ease and surface finish shaping machine is preferred

Drilling of holes at ends of both sides

The holes are drilled with respect to suitable dimensions by using drilling machine

Fabrication of Slider Wood is cut in suitable dimensionThe carpentry operations are performed here

Fabrication of Frame A frame has to withstand the load of the crank as well as the connecting rod to avoid disturbanceA wood plank may be chosen to avoid breakage and also prevent noiseThe frame is to be cut into required dimensions using handsaw and chiselThe frame is to be tightened with the help of adhesives and screws for rigid supportGrinding may be done for a smooth surface finish

Machine tools

Shaping machines

Power-driven saws

Slotter machines

Applications

ConclusionThe purpose of the project is to design and construct a kinematic quick return device. Beginning with general research into quick return devices, the project has to follow a methodology of determining the design space, building a mathematical model and then implementing that model. The design process as a whole has to be experienced from start to finish and is to be incorporated as a multitude of different aspects of engineering. Designing this mechanism will be an excellent experience in tackling a design project where the majority of constraints are self-imposed. The final design produced will be an effective one. Hopefully, with a little work, the mechanism will be operational and seen by future kinematics students for years to come.

ACTIVITY TIMELINEProject Approval July

Consulting Guide & Background Research

August

Proposing A New Design August

Design Specifications September

Software Learning October & November

Software Implementation And Analysis

February

Presenting The Project March

PROJECT PLAN

Methodology Design of links

Analysis of links at various positions

Remodification of links (If required )

Implementation

Fabrication

Performance test

BIBLIOGRAPHY

Theory of Machines by R.S. Khurmi and J.K.Gupta

Design of Machine Elements by R.S. Khurmi and J.K.Gupta

Theory of Machines by Ratan

Manufacturing Technology by P N Rao

http://www.morldtechgossips.com/2012/05/fabrication-of-slider-crank-unit.html