design, fabrication and analysis of crank and slotted lever quick return mechanism

MUFFAKHAM JAH COLLEGE OF ENGINEERING AND

TECHNOLOGY

PROJECT SEMINARPROJECT GUIDE: D.SRINIVAS RAO

(ASSOCIATE PROFESSOR)

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 , FABRICATION AND ANALYSIS OF CRANK AND

SLOTTED LEVERQUICK RETURN MECHANISM

Introduction Defining the Problem Design ANSYS Validation Analysis Manufacturing and Fabrication Future Scope Application Conclusion Bibliography

INDEX

Quick return mechanism, (QRM), is used in machines like Shaper, Planar, Slotter.

INTRODUCTION

Whitworth Quick Return Mechanism

Crank and Slotted Lever Quick Return Mechanism

Lower Quick Return Ratio

Vibrations due to non linear velocity

Defining Problem

Rigid structure

Selection of material

Changing the slider height

Overcoming the problem

1.Link lengths

2.Forces acting on each link

3.Selecting materials

4.Suitable cross section

5.Power Calculations

Factors To Be Considered In Design

Design

Specifications

Stroke length = 270mm

Quick return ratio = 5/3

No. of strokes/min = 100 strokes/min

Crank Length = 75mm

Length of Coupler =100 mm

Link Lengths

Length of AC =r/cos(90-α/2)= 75/cos(68)= 200 mm

Length of slotted lever (AP)=P1Q/sin(90-α/2)= 135/sin(22)= 360 mm

Length of AR= AQ + QR= AP cos (90-α/2) + PR sin(90-α/2)= 360 cos(22) + 100 sin(22)= 375 mm

Calculation of Forces F6 = τAl *d* w F6 = 50*2*5 F6 = 500N F5 = F6 /cos(90-α/2) F5 = 500 /68 F5 = 539N F4 =F5 = 539 N

Dynamic Analysis

Mean Cutting Velocity = L*S* (360/α)= 270*100*(360/136) = 71.47 m/min

Cutting Power = F6 * Vmean = 596 W Power required at Crank Pin = Power / η

= 596/0.8= 745 W

L = length of strokeS = number of strokes / minuteη= mechanical efficiency

Power Calculations

Design of Crank Pin Torque at Crank Pin (Tcr) = (P*60)/(2*π*N)

= (745*60) /(2*π*100)= 71.14 N-m

Force at Crank Pin (Fcr) = Torque / crank radius= (71.14*1000) / 75= 948 N

Max Force at Crank Pin (Fcrm) = Fcr * I.F= 948*2= 1896 N

Diameter of Crank Pin = sqrt(4F/πτ)=sqrt(4*1896 / π*50)=7 mm

=8 mm (standard size pin)

Design of Shaft

Torque acting on shaft =(P*60)/(2*π*N) =(745*60)/(2*π*100) = 142 N-m

Diameter of the shaft (d)=cube root(16T/ πτ)=cube root(16*142*1000 /π*75)= 20 mm

Design Of Slotted BarMaximum Force acting on Slotted Bar = 539 * Impact Load Factor

= 539*3 = 1617NCross-sectional Area Of Crank = Max Load / Permissible Stress

= 1617/30 = 54 mm2 ………..1

ANSYS

•ANSYS is a general purpose software, used to simulate interactions of all disciplines of physics, structural, vibration, fluid dynamics, heat transfer and electromagnetic for engineers.

•To validate the design QRM structural analysis where used.

•Static Analysis-Used to determine displacements, stresses, etc. under static loading conditions. Both linear and nonlinear static analyses.

View of the model afterApplying loads

Meshed model

SLOTTED LEVER

Deformed + Undeformedshape

Displacement Vector Sum

Von Mises Stresses Principle Stresses

COUPLER LINK

View of the model afterApplying loads

Meshed Model

Displacement Vector Sum Von Mises Stresses

RAM

View of the model after applyingloads

Meshed Model

Meshed Model after applying Loads Displacement Vector Sum

Graphical Method

Analytical Method

Software Method

Experimental Method

Analysis of Mechanism

Graphical Method

Graphical method starts with position analysis by simply drawing the linkage mechanism to scale. Then the velocity analysis is performed which requires the angular position of the links to be determined beforehand. Similarly it is necessary to know angular velocities of links for acceleration analysis. Thus, the sequence for kinematic analysis of mechanisms is - position analysis, then velocity analysis and then acceleration 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

MATLAB ANALYSIS

Graph: Instantaneous slider velocity Vs Crank angle

Variation in cutting force with variation in crank angle for different slider heights

EXPERIMENTAL SETUP

Crank Angle

Slider Position

0 10

20 15

40 20

60 40

80 65

100 100

120 140

Crank Angle

Slider Position

220 260

240 240

260 220

280 175

320 70

340 35

360 0

Crank Angle Slider Position

140 180

180 230

200 245

EXPERIMENTAL OBSERVATIONS

SAMPLE CALCULATION OF VELOCITY

At 100 rpm time required for 20 degrees= 20/(100*360)

= 1/30 s

Velocity of the slider at beginning = d/tof the stroke

= 5 / (1/30)

= 0,15 m/s

Velocity of the slider at middle of the = 50 / (1/30)stroke

= 1.5 m/s

Velocity of the slider at the end of = 35 / (1/30)the stroke

= 1.05 m/s

Manufacturing and Fabrication

Fabrication is an industrial term refers to building metal structures by cutting, machining and drilling.

For construction of mechanism in these project billets standard of sizes were taken.

Some of the machine tools used where centre lathe machine, radial drilling machine, tapping, vertical milling machine, grinding machine, files, hydraulic press machine.

Shaft

Machine tools used:

Lathe

Operations performed:

Facing

Turning

Circlip groves

Chamfering

Bull Gear

Machine tools used

LatheAC Arc Welding MachineRadial Drilling MachineVertical Milling Machine

Operations performed:

FacingTurningWeldingDrillingMillingChamfering

Slotted Lever

Machine tools used

Radial Drilling Machine

Vertical Milling Machine

Bench Grinder

Operations performed:

Drilling

Milling

Grinding

Coupler Link

Machine tools used

Radial Drilling Machine

Bench Grinder

Operations performed:

Drilling

Grinding

Guide ways

Machine Tools Used

Hydraulic Press Machine

Radial Drilling Machine

Operations

Pressing to required shape

Drilling

Filing

RamMachine Tools Used

Hydraulic Press Machine

Radial Drilling Machine

Tapping equipments

Operations

Pressing to required shape

Drilling

Tapping

Filing

Frame

Machine Tools Used

Band Saw Machine

Drilling Machine

Operations

Cutting

Slotting

Drilling

Future Scope

• Accurate instantaneous velocity measurement can be done by using precise instruments.

• Comparison can be made with Whitworth Quick Return Mechanism.

• Vibration analysis can be performed.

• Model can be made to achieve higher quick return ratio.

• Kinematic and dynamic analysis can be performed.

Machine tools

Shaping machines

Power-driven saws

Slotter machines

Applications

Conclusion• Quick return ratio is limited to strength of the material. By incorporating stronger materials QRR can be increased.

• Backlash can be minimized by choosing close tolerances and proper assembly techniques.

• With increase in slider height, QRR increases.

• Friction at the interface of guide ways and ram can be minimized by using turcite tape.

• Ram velocity varies from zero at beginning, maximum at middle of the stroke and zero at the end.

BIBLIOGRAPHY• R.S Khurmi & J.K Gupta• Joseph E. Shigley• S S Rattan• Thomas Bevan•http://engineering.myindialist.com/2013/kinematic-inversions-of-four-bar-chain-slider-crank-and-double-slider-crank-mechanism/•https://www.wisc-online.com/learn/career-clusters/stem/eng20704/quick-return-mechanism-velocity-calculations•http://theengineeringdiary.blogspot.in/2011/06/crank-and-slotted-lever-quick-return.htmlhttp://www.quora.com/What-are-differences-between-crank-and-slotted-lever-mechanisms-and-a-Whitworth-quick-return-mechanism