09-11-2016, 12:18 PM
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INTRODUCTION
A Sleeve and cotter joint is used to connect two round rods or bars. In this type of joint, a sleeve or muff is used over the two rods and then two cotters(one on each rod end) are inserted in the holes provided for them in sleeve or rods. The taper of cotter is usually 1 in 24. It may be noted that the taper sides of the two cotters should face each other. The clearance is so adjusted that when the cotters are driven in, the two rods come closer to each other thus making the joint tight.
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A sleeve and cotter joint contains the following parts:
1. Two Sleeves
2. Two wedged shaped tapered cotters
3.A Socket
Two cylindrical rods, which are to be joined, are aligned coaxially. Their similar ends are made to touch each other and their slots are made symmetrical to each other(preferably pointing upwards). Sleeve is then placed over them. It’s slots are aligned with the slots of the cylindrical rods. Two cotters are inserted into the aligned slots.
In a sleeve and cotter joint, the cut slots are always made a little bit wider than the width of the cotter in order to promote wedging action of the cotters over the slots. This clearance is called cotter clearance.
DESIGN CALCULATIONS
Since the load is applied on sleeve the maximum force that a sleeve can withstand without failure is given by:
P = {π/4*[ds2-dr2]-(ds-dr)*t}*U
Where
ds = diameter of sleeve
U = ultimate yield strength of material
P = maximum load
t = thickness of cotter
P = {π/4*[322-252]-(32-25)*8}*460
= 118391N
DESIGN DIMENSIONS
DESIGN PROCESS
The modeling and design of joint is made on CREO.
The components are made individually according to drawing shown above.
The components are now assembled and saved as STEP or IGES file format which can be imported to ANSYS.
ANSYS
This is an analysis software which allows a designer to analyze a object or component with application of real time forces upon our component.
Results which are obtained on the ANSYS will allow designer to evaluate assembly made in CREO.
Meshing can be controlled in components to obtain a better output.
BOUNDARY CONDITIONS
The boundary conditions which are applied the system are:
1. Standard earth gravity
2. force
3. fixed support
Now these conditions are solved.
RESULTS
The important solutions to be obtained are
Total deformation Equivalent stresses
ADVANTAGES OF SLEEVE AND COTTER JOINT
This joint is the simplest joint in existence.
It is quite rigid and can take both tensile and compressive loads.
It can be easily assembled and dismantled
DISADVANTAGES OF SLEEVE AND COTTER JOINT
Rectangular rods and dissimilar cylindrical rods cannot be connected using this joint.
Unlike the universal joints, a sleeve and cotter joint does not allow angular misalignment between its cylindrical members.
It cannot connect cylindrical members which undergo rotation.
Applications
It is used in the connection of piston rod to the cross head of the steam engine.
it is used to joining the fixed or moving shaft...
It is used to connect two rods subjected on axial load.
A cotter is a flat wedge-shaped piece of steel which is used to connect rigidly two rods which transmit motion in the axial direction (tensile or compressive forces) without rotation.
CONCLUSION
The design has given positive results in analysis.
The cotter joint made above can sustain the loads applied on it.