MACINE DESIGN AND CAD II

Project Title

C CLAMPSupervised by

Engr.Nazeer Ahmed Anjum

Made by

Masood ur Rehman-----------------07-ME-14Mushood Ahmed--------------------07-ME-24Rameez Khalid----------------------07-ME-26Muhammad Adnan Rasheed ------07-ME-32Mohsin abbas------------------------07-ME-36

DEPARTMENT OF MECHANICAL ENGINEERINGUNIVERSITY OF ENGINEERING AND TECHNOLOGY TAXILA

PREFACE

The project has been given in order to increase the interest and curiosity in the students, the topic matter has been made more effective by adding figures and diagrams.

There is always a room for the improvement, new ideas, continuous research, national demands and aspirations; and the present effort is also a ring of this chain. Anyway, I hope that the teachers, students and the concerned people will continuously keep me informed of their opinions about the

it.Above all, we thank Almighty ALLAH, who provided me the opportunity and gave me the

strength to undertake the work of public interest.

ACKNOLWLEDGMENT

All thanks to Almighty Allah Who gave us capability to enhance our vision and ability by completion of this project.we greatly indebted to our teacher Engr. Nazeer Ahmed Anjum for providing us some moments of his cruical and so much busy routine. He has been a constant

encouraging hand back up for us during the whole project advancement.

Dedicated to

soldiers of pakisatn who spent sleepless nights on borders to make us sleep peacefully.

Contents

Introduction to C-clampClassificationUses of C-clampMain parts of C-clampMaterialConstruction Modes of failureDesign procedure

Introduction of C-clamp

A C-clamp is a type of clamp device typically used to hold a wood or metalwork piece, and are often used in, but are not limited to, carpentry and welding. These clamps are called "C" clamps because of their C shaped frame,

An open C-clamp

C-clamps are typically made of steel or cast iron, though smaller clamps may be made of pot metal. At the top of the "C" is usually a small flat edge. At the bottom is a threaded hole through which a large threaded screw protrudes. One end of this screw contains a flat edge of similar size to the one at the top of the frame, and the other end usually a small metal bar, perpendicular to the screw itself, which is used to gain leverage when tightening the clamp. When the clamp is completely closed, the flat end of the screw is in contact with the flat end on the frame.

CLASSIFICATION OF CLAMPS

C-clamps are classified as:

Adjustable clamps

String clamps

One hand bar clamps

USAGE

When the clamp is actually used, it is very rare that this occurs. Generally some other object or objects will be contained between the top and bottom flat edges.A C-clamp is used by turning the screw through the bottom of the frame until the desired state is reached. In the case that the clamp is being tightened, this is when the objects being secured are satisfactorily secured between the flat end of the screw and the flat end of the frame. If the clamp is being loosened, this is when a sufficient amount of force has relieved to allow the secured objects to be moved.

Usually c-clamps are used in the following fields:

1. Metal working.2. Woodworking.3. welding

Main Parts of C-clampHandle:Sliding bar for tightening and loosening of screw, thereby, opening and closing the jaw.Adjusting Screw:Threaded shank whose rotation is controlled by the handle; it moves the jaw towards and away from the piece to be clamped.

Frame:Rigid metal support in the shape of C having fixed jaw at one end while other end contain hole for adjusting screw.

Throat:Opening made by the frame.

Swivel Head:End of tightening screw: it pivots to adjust irregularly shaped object.

Moveable Jaw:Smooth or straited part that presses an object against fixed jaw.

Fixed Jaw:Smooth or striated part against which moveable jaw presses an object.

MATERIAL:The cast iron is obtained by re-melting pig biron withj coke and limestone in a furnace known as cupola.It is primarily an alloy of iron and carbon.The carbon contents in cast ironvaries from 1.7 pertcent to 4.5 percent.It also contains small amounts of silicon,manganese,phosphorus and sulphur.Since iron is brittle material,therefore,it can not be used in those parts of machines which are subjected to shocks. The properties of cast iron which make it a valuable material for engineering purposes are ,its low cast,good casting characteristics,high compressive strength,wear resistance and good machineability. Following are the values of ultimate strength of cast iron:1:Tensile strength=100 to 200 MPa2:Compressive strength=400 to 1000 MPa3:Shear strength=120 MPa F.O.S = 5 to 6

Factor of safety =

CONSTRUCTION

In a c-clamp at the top of the "c" is usually a small flat edge. At the bottom is a threaded hole through which a large threaded screw protrudes. One end of this screw contains a flat edge of similar size to the one at the top of the frame, and the other end usually a small metal bar, perpendicular to the screw itself, which is used to gain leverage when tightening the clamp. When the clamp is completely closed, the flat end of the screw is in contact with the flat end on the frame. When the clamp is actually used, it is very rare that this occurs. Generally some other object or objects will be contained between the top and bottom flat edges.

Modes of Failure:

Tensile failure

Shear failure

Bending failure

Compressive failure

Design process of c- clamp

Tensile failure of component(a)

P = δt × A Where A is area P = δt × bt

Tensile failure of component fig (b)

P = δt(b't')

Fig(b)

Shear Failure of Frame fig(c) Fig(a)

Where A’ =2bt + b't' Fig(c)

Compressive Failure of Screw

Pc = δc ×

Cross section of screw

Bending Failure of Frame

Where

Assumption:b=4.5t

PROBLEM

Design a c-clamp which can carry load of 7973.27 N

F.O.S.=5SOLUTION

Tensile failure of frame component

=27.273(4.5)

Tensile failure of component frame shown in fig.

where b`=3.2 t`

t`=9.2 mm

Compressive failure of screw

A

Design check

= A=292.33

which is higherDesign is not safe so we calculate again

=24

t=4 mm

7973.27=t`=10.18 mm where b`=3.2t`

Thus dimensions for designing a C clamp are:

Limitations of design:The load which can be mounted in C clamp isP=7973.27 N which approximately 8000NFor this weight our design is safe.